<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva, formerly WebFilings-->
<!-- -->
<linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedBalanceSheets" xlink:href="agnc-20150331.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedBalanceSheetsParentheticals" xlink:href="agnc-20150331.xsd#ConsolidatedBalanceSheetsParentheticals" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedStatementOfStockholdersEquity" xlink:href="agnc-20150331.xsd#ConsolidatedStatementOfStockholdersEquity" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="agnc-20150331.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:href="agnc-20150331.xsd#ConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstruments" xlink:href="agnc-20150331.xsd#DerivativeAndOtherHedgingInstruments" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsEffectOfDerivativeInstrumentsNotDesignatedAsHedgesOnComprehensiveIncomeStatementDetails" xlink:href="agnc-20150331.xsd#DerivativeAndOtherHedgingInstrumentsEffectOfDerivativeInstrumentsNotDesignatedAsHedgesOnComprehensiveIncomeStatementDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsFairValueInformationDetails" xlink:href="agnc-20150331.xsd#DerivativeAndOtherHedgingInstrumentsFairValueInformationDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsNarrativeDetails" xlink:href="agnc-20150331.xsd#DerivativeAndOtherHedgingInstrumentsNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsRemainingInterestRateSwapTermDetails" xlink:href="agnc-20150331.xsd#DerivativeAndOtherHedgingInstrumentsRemainingInterestRateSwapTermDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsSummaryOfOutstandingInterestRateSwapsDetails" xlink:href="agnc-20150331.xsd#DerivativeAndOtherHedgingInstrumentsSummaryOfOutstandingInterestRateSwapsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsTables" xlink:href="agnc-20150331.xsd#DerivativeAndOtherHedgingInstrumentsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsTbaSecuritiesByCouponAndIssuerDetails" xlink:href="agnc-20150331.xsd#DerivativeAndOtherHedgingInstrumentsTbaSecuritiesByCouponAndIssuerDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsUsTreasurySecuritiesDetails" xlink:href="agnc-20150331.xsd#DerivativeAndOtherHedgingInstrumentsUsTreasurySecuritiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/DocumentAndEntityInformation" xlink:href="agnc-20150331.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/FairValueMeasurements" xlink:href="agnc-20150331.xsd#FairValueMeasurements" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/FairValueMeasurementsDetails" xlink:href="agnc-20150331.xsd#FairValueMeasurementsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/FairValueMeasurementsTables" xlink:href="agnc-20150331.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InterimConsolidatedFinancialStatements" xlink:href="agnc-20150331.xsd#InterimConsolidatedFinancialStatements" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecurities" xlink:href="agnc-20150331.xsd#InvestmentSecurities" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesComponentsOfInvestmentSecuritiesDetails" xlink:href="agnc-20150331.xsd#InvestmentSecuritiesComponentsOfInvestmentSecuritiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesNarrativeDetails" xlink:href="agnc-20150331.xsd#InvestmentSecuritiesNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfAgencySecuritiesEstimatedWeightedAverageLifeClassificationsDetails" xlink:href="agnc-20150331.xsd#InvestmentSecuritiesSummaryOfAgencySecuritiesEstimatedWeightedAverageLifeClassificationsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfChangesInAccumulatedOciForAvailableForSaleSecurityDetails" xlink:href="agnc-20150331.xsd#InvestmentSecuritiesSummaryOfChangesInAccumulatedOciForAvailableForSaleSecurityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfContinuousUnrealizedLossPositionsOfAvailableForSaleSecurityDetails" xlink:href="agnc-20150331.xsd#InvestmentSecuritiesSummaryOfContinuousUnrealizedLossPositionsOfAvailableForSaleSecurityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfInvestmentInAgencySecurityDetails" xlink:href="agnc-20150331.xsd#InvestmentSecuritiesSummaryOfInvestmentInAgencySecurityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfNetGainFromSaleOfAgencySecuritiesDetails" xlink:href="agnc-20150331.xsd#InvestmentSecuritiesSummaryOfNetGainFromSaleOfAgencySecuritiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/InvestmentSecuritiesTables" xlink:href="agnc-20150331.xsd#InvestmentSecuritiesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/Organization" xlink:href="agnc-20150331.xsd#Organization" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/OrganizationDetails" xlink:href="agnc-20150331.xsd#OrganizationDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssets" xlink:href="agnc-20150331.xsd#PledgedAssets" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsAssetsPledgedAsCollateralDetails" xlink:href="agnc-20150331.xsd#PledgedAssetsAssetsPledgedAsCollateralDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsAssetsPledgedFromCounterpartiesDetails" xlink:href="agnc-20150331.xsd#PledgedAssetsAssetsPledgedFromCounterpartiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsNarrativeDetails" xlink:href="agnc-20150331.xsd#PledgedAssetsNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsOffsettingAssetsAndLiabilitiesDetails" xlink:href="agnc-20150331.xsd#PledgedAssetsOffsettingAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsSecuritiesPledgedAsCollateralDetails" xlink:href="agnc-20150331.xsd#PledgedAssetsSecuritiesPledgedAsCollateralDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/PledgedAssetsTables" xlink:href="agnc-20150331.xsd#PledgedAssetsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebt" xlink:href="agnc-20150331.xsd#RepurchaseAgreementsAndOtherDebt" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtNarrativeDetails" xlink:href="agnc-20150331.xsd#RepurchaseAgreementsAndOtherDebtNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtRepurchaseArrangementsAndWeightedAverageInterestRatesClassifiedByOriginalMaturitiesDetails" xlink:href="agnc-20150331.xsd#RepurchaseAgreementsAndOtherDebtRepurchaseArrangementsAndWeightedAverageInterestRatesClassifiedByOriginalMaturitiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtTables" xlink:href="agnc-20150331.xsd#RepurchaseAgreementsAndOtherDebtTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquity" xlink:href="agnc-20150331.xsd#StockholdersEquity" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquityAccumulatedOtherComprehensiveIncomeLossDetails" xlink:href="agnc-20150331.xsd#StockholdersEquityAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquityCommonStockRepurchaseProgramDetails" xlink:href="agnc-20150331.xsd#StockholdersEquityCommonStockRepurchaseProgramDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquityPreferredStockDetails" xlink:href="agnc-20150331.xsd#StockholdersEquityPreferredStockDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/StockholdersEquityTables" xlink:href="agnc-20150331.xsd#StockholdersEquityTables" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SubsequentEvent" xlink:href="agnc-20150331.xsd#SubsequentEvent" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SubsequentEventDetails" xlink:href="agnc-20150331.xsd#SubsequentEventDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="agnc-20150331.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:href="agnc-20150331.xsd#SummaryOfSignificantAccountingPoliciesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesPolicy" xlink:href="agnc-20150331.xsd#SummaryOfSignificantAccountingPoliciesPolicy" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedBalanceSheets" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedBalanceSheetsParentheticals" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedStatementOfStockholdersEquity" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_19AF0DC6F6758CA72DAF2083AE4F207D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_StatementTable_19AF0DC6F6758CA72DAF2083AE4F207D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_6FD74DB31FED83DA81362083AE4F8BE2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_19AF0DC6F6758CA72DAF2083AE4F207D" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_6FD74DB31FED83DA81362083AE4F8BE2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_263E6DB460AA3C6FF8E12083AE4FE1BF_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6FD74DB31FED83DA81362083AE4F8BE2" xlink:to="loc_us-gaap_EquityComponentDomain_263E6DB460AA3C6FF8E12083AE4FE1BF_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_263E6DB460AA3C6FF8E12083AE4FE1BF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6FD74DB31FED83DA81362083AE4F8BE2" xlink:to="loc_us-gaap_EquityComponentDomain_263E6DB460AA3C6FF8E12083AE4FE1BF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaap_PreferredStockMember_EE5EC20841F1541DEBCC2083AE4F20DC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_263E6DB460AA3C6FF8E12083AE4FE1BF" xlink:to="loc_us-gaap_PreferredStockMember_EE5EC20841F1541DEBCC2083AE4F20DC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_B8602994805F2029CE8B2083AE506CCF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_263E6DB460AA3C6FF8E12083AE4FE1BF" xlink:to="loc_us-gaap_CommonStockMember_B8602994805F2029CE8B2083AE506CCF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_C6BEDABB7B280F0E36A92083AE508C75" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_263E6DB460AA3C6FF8E12083AE4FE1BF" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_C6BEDABB7B280F0E36A92083AE508C75" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_9A36DCF158C040AB04F42083AE503691" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_263E6DB460AA3C6FF8E12083AE4FE1BF" xlink:to="loc_us-gaap_RetainedEarningsMember_9A36DCF158C040AB04F42083AE503691" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_060A1B45F524B5B01FAC2083AE503526" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_263E6DB460AA3C6FF8E12083AE4FE1BF" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_060A1B45F524B5B01FAC2083AE503526" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_E6E35B414939E79E8DD62083AE506B43" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_StockholdersEquity_E6E35B414939E79E8DD62083AE506B43" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_F2E9E6C88EFED5C9E56C2083AE50C117" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_F2E9E6C88EFED5C9E56C2083AE50C117" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_09514B58B38138DFE94C2083AE5060AE" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_09514B58B38138DFE94C2083AE5060AE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_678460261853777DA05A2083AE50B5E5" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_NetIncomeLoss_678460261853777DA05A2083AE50B5E5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_401295918BA8CBEF23C72083AE50FC41" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_401295918BA8CBEF23C72083AE50FC41" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_F8D2736994C33B0E4F962083AE50831C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_401295918BA8CBEF23C72083AE50FC41" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_F8D2736994C33B0E4F962083AE50831C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_290C20931F22984C86182083AE501EA9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_401295918BA8CBEF23C72083AE50FC41" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_290C20931F22984C86182083AE501EA9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_3335234E016BB5D361D72083AE51B69F" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_3335234E016BB5D361D72083AE51B69F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_8039098F9AFD9040FDD82083AE516776" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_8039098F9AFD9040FDD82083AE516776" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DividendsPreferredStockCash" xlink:label="loc_us-gaap_DividendsPreferredStockCash_E62B906EF9AF3A1E0A932083AE518D57" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_DividendsPreferredStockCash_E62B906EF9AF3A1E0A932083AE518D57" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DividendsCommonStockCash" xlink:label="loc_us-gaap_DividendsCommonStockCash_A62498DBB0291333B4242083AE51E6B6" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9BCD3927C3D7C43081E52083AE50E71B" xlink:to="loc_us-gaap_DividendsCommonStockCash_A62498DBB0291333B4242083AE51E6B6" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstruments" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsEffectOfDerivativeInstrumentsNotDesignatedAsHedgesOnComprehensiveIncomeStatementDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_C749D520518288A8B30620EA114B2FE3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:to="loc_us-gaap_DerivativeTable_C749D520518288A8B30620EA114B2FE3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PositionAxis" xlink:label="loc_us-gaap_PositionAxis_34F76638FD3FC717805E20EA114B4012" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_C749D520518288A8B30620EA114B2FE3" xlink:to="loc_us-gaap_PositionAxis_34F76638FD3FC717805E20EA114B4012" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_15495D6FA66074AE695F20EA114B398A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_34F76638FD3FC717805E20EA114B4012" xlink:to="loc_us-gaap_PositionDomain_15495D6FA66074AE695F20EA114B398A_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PositionDomain" xlink:label="loc_us-gaap_PositionDomain_15495D6FA66074AE695F20EA114B398A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_34F76638FD3FC717805E20EA114B4012" xlink:to="loc_us-gaap_PositionDomain_15495D6FA66074AE695F20EA114B398A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShortMember" xlink:label="loc_us-gaap_ShortMember_310AE7D8AA40123722C920EA114BE306" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_15495D6FA66074AE695F20EA114B398A" xlink:to="loc_us-gaap_ShortMember_310AE7D8AA40123722C920EA114BE306" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LongMember" xlink:label="loc_us-gaap_LongMember_5B7CC6BC57DD54D6F7D520EA114B947E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_15495D6FA66074AE695F20EA114B398A" xlink:to="loc_us-gaap_LongMember_5B7CC6BC57DD54D6F7D520EA114B947E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_28AD0675962D7640868820EA114CC18B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_C749D520518288A8B30620EA114B2FE3" xlink:to="loc_us-gaap_HedgingDesignationAxis_28AD0675962D7640868820EA114CC18B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_F74AB950D90DF4E9FD9620EA114C27B4_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_28AD0675962D7640868820EA114CC18B" xlink:to="loc_us-gaap_HedgingDesignationDomain_F74AB950D90DF4E9FD9620EA114C27B4_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_F74AB950D90DF4E9FD9620EA114C27B4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_28AD0675962D7640868820EA114CC18B" xlink:to="loc_us-gaap_HedgingDesignationDomain_F74AB950D90DF4E9FD9620EA114C27B4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NondesignatedMember" xlink:label="loc_us-gaap_NondesignatedMember_15196FAB8795BBEB5B6020EA114C3021" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_F74AB950D90DF4E9FD9620EA114C27B4" xlink:to="loc_us-gaap_NondesignatedMember_15196FAB8795BBEB5B6020EA114C3021" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_80AC571EA084BA83736E20EA114C12A9" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_C749D520518288A8B30620EA114B2FE3" xlink:to="loc_us-gaap_InvestmentTypeAxis_80AC571EA084BA83736E20EA114C12A9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_DACD006F1E7041C9DE5420EA114C09F4_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_80AC571EA084BA83736E20EA114C12A9" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_DACD006F1E7041C9DE5420EA114C09F4_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_DACD006F1E7041C9DE5420EA114C09F4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_80AC571EA084BA83736E20EA114C12A9" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_DACD006F1E7041C9DE5420EA114C09F4" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OtherDerivativesMember" xlink:label="loc_agnc_OtherDerivativesMember_3AAF84696ECD4D1B4D7420EA114C865E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_DACD006F1E7041C9DE5420EA114C09F4" xlink:to="loc_agnc_OtherDerivativesMember_3AAF84696ECD4D1B4D7420EA114C865E" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_23E6062F47BAA49517C420EA114CCB6C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_DACD006F1E7041C9DE5420EA114C09F4" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_23E6062F47BAA49517C420EA114CCB6C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_E555AFC48F87C86487F020EA114CF7D3" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_C749D520518288A8B30620EA114B2FE3" xlink:to="loc_us-gaap_DerivativeByNatureAxis_E555AFC48F87C86487F020EA114CF7D3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_A9B089379C6E954BC68A20EA114CAD74_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_E555AFC48F87C86487F020EA114CF7D3" xlink:to="loc_us-gaap_DerivativeNameDomain_A9B089379C6E954BC68A20EA114CAD74_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_A9B089379C6E954BC68A20EA114CAD74" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_E555AFC48F87C86487F020EA114CF7D3" xlink:to="loc_us-gaap_DerivativeNameDomain_A9B089379C6E954BC68A20EA114CAD74" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_F464AE874C9CB17E526F20EA114CE43B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_A9B089379C6E954BC68A20EA114CAD74" xlink:to="loc_agnc_ReceiverSwaptionMember_F464AE874C9CB17E526F20EA114CE43B" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PayerSwaptionMember" xlink:label="loc_agnc_PayerSwaptionMember_FA9CD7073C5262A7461520EA114C628B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_A9B089379C6E954BC68A20EA114CAD74" xlink:to="loc_agnc_PayerSwaptionMember_FA9CD7073C5262A7461520EA114C628B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_452E063DA6DED7833A6B20EA114CA392" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_A9B089379C6E954BC68A20EA114CAD74" xlink:to="loc_us-gaap_FutureMember_452E063DA6DED7833A6B20EA114CA392" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_E700AA3DDAA8E0BBAF5B20EA114C2FB5" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_C749D520518288A8B30620EA114B2FE3" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_E700AA3DDAA8E0BBAF5B20EA114C2FB5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_E700AA3DDAA8E0BBAF5B20EA114C2FB5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_E700AA3DDAA8E0BBAF5B20EA114C2FB5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PutOptionMember" xlink:label="loc_us-gaap_PutOptionMember_9826BB714B441B705BF720EA114CAD52" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:to="loc_us-gaap_PutOptionMember_9826BB714B441B705BF720EA114CAD52" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwaptionMember" xlink:label="loc_us-gaap_InterestRateSwaptionMember_3F1783F52C7DCCBE0ED720EA114CDA9E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:to="loc_us-gaap_InterestRateSwaptionMember_3F1783F52C7DCCBE0ED720EA114CDA9E" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_E01628785572873A9B9020EA114CAAC4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:to="loc_agnc_ReceiverSwaptionMember_E01628785572873A9B9020EA114CAAC4" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PayerSwaptionMember" xlink:label="loc_agnc_PayerSwaptionMember_BBD2EB44BF44345B9B9720EA114CC9EB" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:to="loc_agnc_PayerSwaptionMember_BBD2EB44BF44345B9B9720EA114CC9EB" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_048A8AF785195ADB719E20EA114C1C29" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_048A8AF785195ADB719E20EA114C1C29" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_466C3EA6C2F8851FE87220EA114C444B" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:to="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_466C3EA6C2F8851FE87220EA114C444B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_6EC270F0531FDBC9273620EA114C1675" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:to="loc_us-gaap_InterestRateSwapMember_6EC270F0531FDBC9273620EA114C1675" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_010982BC7FF38BBCF84220EA114C14DE" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66B2F9E14998478EEA9720EA114C9947" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_010982BC7FF38BBCF84220EA114C14DE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_BA049B0FB0ABD88877AD20EA114DE501" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_C749D520518288A8B30620EA114B2FE3" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_BA049B0FB0ABD88877AD20EA114DE501" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_BA049B0FB0ABD88877AD20EA114DE501" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_BA049B0FB0ABD88877AD20EA114DE501" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_A8446376F87DA08C3E1120EA114D2186" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_A8446376F87DA08C3E1120EA114D2186" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_8597D8039CC23E036D1B20EA114DFCFC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340" xlink:to="loc_us-gaap_InterestRateSwapMember_8597D8039CC23E036D1B20EA114DFCFC" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_5C9A957F420B7BDB103120EA114D0CCC" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340" xlink:to="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_5C9A957F420B7BDB103120EA114D0CCC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PutOptionMember" xlink:label="loc_us-gaap_PutOptionMember_78E0B363718983341DE120EA114D66CD" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340" xlink:to="loc_us-gaap_PutOptionMember_78E0B363718983341DE120EA114D66CD" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestRateSwapsMember" xlink:label="loc_agnc_InterestRateSwapsMember_3FA824E859905B123F8920EA114DEE96" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340" xlink:to="loc_agnc_InterestRateSwapsMember_3FA824E859905B123F8920EA114DEE96" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_3C3474AB53137FE8FE2F20EA114D01DB" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340" xlink:to="loc_agnc_ReceiverSwaptionMember_3C3474AB53137FE8FE2F20EA114D01DB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_EF91B9132A23FDFC686A20EA114D3CD8" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_56B271904BAE03C9039220EA114DC340" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_EF91B9132A23FDFC686A20EA114D3CD8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeAxis" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityTypeAxis_899A798022921387005C20EA114D3852" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_C749D520518288A8B30620EA114B2FE3" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityTypeAxis_899A798022921387005C20EA114D3852" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeDomain" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_C5D1934B1CC0BDE3304A20EA114D4850_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OptionIndexedToIssuersEquityTypeAxis_899A798022921387005C20EA114D3852" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_C5D1934B1CC0BDE3304A20EA114D4850_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeDomain" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_C5D1934B1CC0BDE3304A20EA114D4850" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OptionIndexedToIssuersEquityTypeAxis_899A798022921387005C20EA114D3852" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_C5D1934B1CC0BDE3304A20EA114D4850" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PutOptionMember" xlink:label="loc_us-gaap_PutOptionMember_B020BF436A318EF7258020EA114D59BD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_C5D1934B1CC0BDE3304A20EA114D4850" xlink:to="loc_us-gaap_PutOptionMember_B020BF436A318EF7258020EA114D59BD" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward" xlink:label="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_5A4B9E0EBAFEBF5EF88820FD44C28932" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:to="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_5A4B9E0EBAFEBF5EF88820FD44C28932" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeLiabilityNotionalAmount" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_456B205C4335A0B7863D20EA114D62EA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_5A4B9E0EBAFEBF5EF88820FD44C28932" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_456B205C4335A0B7863D20EA114D62EA" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod" xlink:label="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod_DB3349078120D454A1D620EA114DBAC9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_5A4B9E0EBAFEBF5EF88820FD44C28932" xlink:to="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsAdditionsDuringPeriod_DB3349078120D454A1D620EA114DBAC9" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod" xlink:label="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod_74E1851FADF433A2096020EA114D7370" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_ChangesinDerivativeandOtherHedgePortfolioRollForward_5A4B9E0EBAFEBF5EF88820FD44C28932" xlink:to="loc_agnc_NotionalAmountOfDerivativesNotDesignatedAsHedgingInstrumentsSettlementExpirationDuringPeriod_74E1851FADF433A2096020EA114D7370" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_AFA22BE6B97061847EF720EA114DC56F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_AFA22BE6B97061847EF720EA114DC56F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TradingSecurities" xlink:label="loc_us-gaap_TradingSecurities_DBB900E611D62F65383620EA114D8DAB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:to="loc_us-gaap_TradingSecurities_DBB900E611D62F65383620EA114D8DAB" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TradingSecuritiesAddedDuringthePeriod" xlink:label="loc_agnc_TradingSecuritiesAddedDuringthePeriod_05FCDB15702095786EF320EA114DF79C" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:to="loc_agnc_TradingSecuritiesAddedDuringthePeriod_05FCDB15702095786EF320EA114DF79C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod" xlink:label="loc_agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod_0B2396530FE1FA33FB6420EA114D0723" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:to="loc_agnc_NotionalAmountOfTradingSecuritiesSettlementExpirationDuringThePeriod_0B2396530FE1FA33FB6420EA114D0723" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_UnrealizedGainLossOnSecurities" xlink:label="loc_us-gaap_UnrealizedGainLossOnSecurities_4CFA5BBABAC447D7435620EA114DFBE6" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:to="loc_us-gaap_UnrealizedGainLossOnSecurities_4CFA5BBABAC447D7435620EA114DFBE6" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GainlossonREITEquitySecurities" xlink:label="loc_agnc_GainlossonREITEquitySecurities_FE71486ADE88FE62A33D20EA114DFE75" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:to="loc_agnc_GainlossonREITEquitySecurities_FE71486ADE88FE62A33D20EA114DFE75" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GainLossOnOtherDebt" xlink:label="loc_agnc_GainLossOnOtherDebt_C194CB0C9EBC521FD24C20EA114D8DE5" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_DEA3E2C3D9156BF1106620EA114D196E" xlink:to="loc_agnc_GainLossOnOtherDebt_C194CB0C9EBC521FD24C20EA114D8DE5" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsFairValueInformationDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_10DEA7CC15B0D4A9D71F20BA10353BFB" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_F7AC501892C6068B92D320BA10330120" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_10DEA7CC15B0D4A9D71F20BA10353BFB" xlink:to="loc_us-gaap_DerivativeTable_F7AC501892C6068B92D320BA10330120" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_0461885027A5592649C120BA1034AF5A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_F7AC501892C6068B92D320BA10330120" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_0461885027A5592649C120BA1034AF5A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_22FE2EBE5EB73EE0F00C20BA1034B638_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_0461885027A5592649C120BA1034AF5A" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_22FE2EBE5EB73EE0F00C20BA1034B638_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_22FE2EBE5EB73EE0F00C20BA1034B638" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_0461885027A5592649C120BA1034AF5A" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_22FE2EBE5EB73EE0F00C20BA1034B638" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_1E40ED4510AABE84BE1B20BA103464C4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_22FE2EBE5EB73EE0F00C20BA1034B638" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_1E40ED4510AABE84BE1B20BA103464C4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_DCC4C4AC3EF9B866DE1020BA1034A504" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_F7AC501892C6068B92D320BA10330120" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_DCC4C4AC3EF9B866DE1020BA1034A504" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_18A9D0E063D9E0134E7920BA1034A8DB_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_DCC4C4AC3EF9B866DE1020BA1034A504" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_18A9D0E063D9E0134E7920BA1034A8DB_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_18A9D0E063D9E0134E7920BA1034A8DB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_DCC4C4AC3EF9B866DE1020BA1034A504" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_18A9D0E063D9E0134E7920BA1034A8DB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_38D0375F1232EB852DBB20BA1034735E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_18A9D0E063D9E0134E7920BA1034A8DB" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_38D0375F1232EB852DBB20BA1034735E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_90942454F271C3806C0220BA1034C61E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_F7AC501892C6068B92D320BA10330120" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_90942454F271C3806C0220BA1034C61E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_26D5D1BDF95D2E03139520BA10346BDF_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_90942454F271C3806C0220BA1034C61E" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_26D5D1BDF95D2E03139520BA10346BDF_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_26D5D1BDF95D2E03139520BA10346BDF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_90942454F271C3806C0220BA1034C61E" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_26D5D1BDF95D2E03139520BA10346BDF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_DA39CC82FA64263E685320BA1034B7C2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_26D5D1BDF95D2E03139520BA10346BDF" xlink:to="loc_us-gaap_InterestRateSwapMember_DA39CC82FA64263E685320BA1034B7C2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwaptionMember" xlink:label="loc_us-gaap_InterestRateSwaptionMember_A61568273DEB9D12182E20BA10345E04" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_26D5D1BDF95D2E03139520BA10346BDF" xlink:to="loc_us-gaap_InterestRateSwaptionMember_A61568273DEB9D12182E20BA10345E04" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_58B644E06226E48126D220BA1034EE0F" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_26D5D1BDF95D2E03139520BA10346BDF" xlink:to="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_58B644E06226E48126D220BA1034EE0F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_0421A6C29D7DD4FBE09120BA1034383D" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_26D5D1BDF95D2E03139520BA10346BDF" xlink:to="loc_us-gaap_FutureMember_0421A6C29D7DD4FBE09120BA1034383D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8F464006D55638CD19AA20BA103452E8" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_F7AC501892C6068B92D320BA10330120" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8F464006D55638CD19AA20BA103452E8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_12AFFAF960D2823A9B4920BA1034CB33_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8F464006D55638CD19AA20BA103452E8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_12AFFAF960D2823A9B4920BA1034CB33_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_12AFFAF960D2823A9B4920BA1034CB33" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8F464006D55638CD19AA20BA103452E8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_12AFFAF960D2823A9B4920BA1034CB33" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_891FA381C5C0BE8D556220BA1035AC7D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_12AFFAF960D2823A9B4920BA1034CB33" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_891FA381C5C0BE8D556220BA1035AC7D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_1528BB0C9D0FEEFAE3DA20BA1035B2BF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_12AFFAF960D2823A9B4920BA1034CB33" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_1528BB0C9D0FEEFAE3DA20BA1035B2BF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_6E22DC70D0EC1EAC75B520BA10353139" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_F7AC501892C6068B92D320BA10330120" xlink:to="loc_us-gaap_DerivativeByNatureAxis_6E22DC70D0EC1EAC75B520BA10353139" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_AC7E7349327FA216769920BA10354C64_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_6E22DC70D0EC1EAC75B520BA10353139" xlink:to="loc_us-gaap_DerivativeNameDomain_AC7E7349327FA216769920BA10354C64_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_AC7E7349327FA216769920BA10354C64" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_6E22DC70D0EC1EAC75B520BA10353139" xlink:to="loc_us-gaap_DerivativeNameDomain_AC7E7349327FA216769920BA10354C64" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_326BC5B1A027D02CCAEC20BA1035218F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_AC7E7349327FA216769920BA10354C64" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_326BC5B1A027D02CCAEC20BA1035218F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_2E6BF36E82881F7F09BA20BA10355052" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10DEA7CC15B0D4A9D71F20BA10353BFB" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_2E6BF36E82881F7F09BA20BA10355052" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_F2F073806B1FB2B5F44720BA10351FFA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10DEA7CC15B0D4A9D71F20BA10353BFB" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_F2F073806B1FB2B5F44720BA10351FFA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeAssets" xlink:label="loc_us-gaap_DerivativeAssets_D8C9532E827A4ECFC31F20BA10353FFD" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10DEA7CC15B0D4A9D71F20BA10353BFB" xlink:to="loc_us-gaap_DerivativeAssets_D8C9532E827A4ECFC31F20BA10353FFD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_D6059CB0AD876E73B7F620BA1035585B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10DEA7CC15B0D4A9D71F20BA10353BFB" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_D6059CB0AD876E73B7F620BA1035585B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FinancialInstrumentsSoldNotYetPurchasedUSGovernmentAndAgencyObligations" xlink:label="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedUSGovernmentAndAgencyObligations_845F34855AA6B40A121820BA1035A351" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10DEA7CC15B0D4A9D71F20BA10353BFB" xlink:to="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedUSGovernmentAndAgencyObligations_845F34855AA6B40A121820BA1035A351" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_Governmentbondsownedandsoldshortnet" xlink:label="loc_agnc_Governmentbondsownedandsoldshortnet_BE32D94FF941343E3B4C20BA1035A9C4" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10DEA7CC15B0D4A9D71F20BA10353BFB" xlink:to="loc_agnc_Governmentbondsownedandsoldshortnet_BE32D94FF941343E3B4C20BA1035A9C4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromSecuritiesPurchasedUnderAgreementsToResell" xlink:label="loc_us-gaap_ProceedsFromSecuritiesPurchasedUnderAgreementsToResell_6DFECE9E1C8B9E2098C120BA1035A561" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_10DEA7CC15B0D4A9D71F20BA10353BFB" xlink:to="loc_us-gaap_ProceedsFromSecuritiesPurchasedUnderAgreementsToResell_6DFECE9E1C8B9E2098C120BA1035A561" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_0F5952E01007837845A920E93CD952E7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_us-gaap_DerivativeTable_0F5952E01007837845A920E93CD952E7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_5AC7757D525042BBDDAF20E93CD9481C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_0F5952E01007837845A920E93CD952E7" xlink:to="loc_us-gaap_DerivativeByNatureAxis_5AC7757D525042BBDDAF20E93CD9481C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_56992DEECA16BC98317720E93CD984E2_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_5AC7757D525042BBDDAF20E93CD9481C" xlink:to="loc_us-gaap_DerivativeNameDomain_56992DEECA16BC98317720E93CD984E2_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_56992DEECA16BC98317720E93CD984E2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_5AC7757D525042BBDDAF20E93CD9481C" xlink:to="loc_us-gaap_DerivativeNameDomain_56992DEECA16BC98317720E93CD984E2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ForwardContractsMember" xlink:label="loc_us-gaap_ForwardContractsMember_21EC21EA595F3325936520E93CD9E374" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_56992DEECA16BC98317720E93CD984E2" xlink:to="loc_us-gaap_ForwardContractsMember_21EC21EA595F3325936520E93CD9E374" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativePositionAxis" xlink:label="loc_agnc_DerivativePositionAxis_6F6A2656128C9A5EFD2720E93CD97C3D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_0F5952E01007837845A920E93CD952E7" xlink:to="loc_agnc_DerivativePositionAxis_6F6A2656128C9A5EFD2720E93CD97C3D" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_E09BB00076B4E28C52DF20E93CD9EFF9_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativePositionAxis_6F6A2656128C9A5EFD2720E93CD97C3D" xlink:to="loc_agnc_DerivativePositionDomain_E09BB00076B4E28C52DF20E93CD9EFF9_default" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_E09BB00076B4E28C52DF20E93CD9EFF9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativePositionAxis_6F6A2656128C9A5EFD2720E93CD97C3D" xlink:to="loc_agnc_DerivativePositionDomain_E09BB00076B4E28C52DF20E93CD9EFF9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_CD0C82AF5293A400F2C520E93CD9BCA5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_E09BB00076B4E28C52DF20E93CD9EFF9" xlink:to="loc_us-gaap_InterestRateSwapMember_CD0C82AF5293A400F2C520E93CD9BCA5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_C0AA4B95AEA79696D4AA20E93CD91671" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_0F5952E01007837845A920E93CD952E7" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_C0AA4B95AEA79696D4AA20E93CD91671" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3646AC8B7EA9E96C236320E93CDA4C1F_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_C0AA4B95AEA79696D4AA20E93CD91671" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3646AC8B7EA9E96C236320E93CDA4C1F_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3646AC8B7EA9E96C236320E93CDA4C1F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_C0AA4B95AEA79696D4AA20E93CD91671" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3646AC8B7EA9E96C236320E93CDA4C1F" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_658A72A4864CE5BD55AB20E93CDA55E3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3646AC8B7EA9E96C236320E93CDA4C1F" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_658A72A4864CE5BD55AB20E93CDA55E3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_90072A19B259C275AAA620E93CDAC99E" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_0F5952E01007837845A920E93CD952E7" xlink:to="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_90072A19B259C275AAA620E93CDAC99E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_8585D9B721616613DD4120E93CDAF51C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_90072A19B259C275AAA620E93CDAC99E" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_8585D9B721616613DD4120E93CDAF51C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_8585D9B721616613DD4120E93CDAF51C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_90072A19B259C275AAA620E93CDAC99E" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_8585D9B721616613DD4120E93CDAF51C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember" xlink:label="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_72F4710E5A7A711AEDEB20E93CDA77EF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_8585D9B721616613DD4120E93CDAF51C" xlink:to="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_72F4710E5A7A711AEDEB20E93CDA77EF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_7FC8A4779C0D55C0E4ED20E93CDACCB9" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_0F5952E01007837845A920E93CD952E7" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_7FC8A4779C0D55C0E4ED20E93CDACCB9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_0A0D05BBB2DA17BB79D120E93CDA398B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_7FC8A4779C0D55C0E4ED20E93CDACCB9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_0A0D05BBB2DA17BB79D120E93CDA398B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_0A0D05BBB2DA17BB79D120E93CDA398B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_7FC8A4779C0D55C0E4ED20E93CDACCB9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_0A0D05BBB2DA17BB79D120E93CDA398B" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestRateSwapsMember" xlink:label="loc_agnc_InterestRateSwapsMember_3CB8DFDF51E3F47E7DD720E93CDA11E6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0A0D05BBB2DA17BB79D120E93CDA398B" xlink:to="loc_agnc_InterestRateSwapsMember_3CB8DFDF51E3F47E7DD720E93CDA11E6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_C2CAB59D58C8F9A0A52720E93CDA79B8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_C2CAB59D58C8F9A0A52720E93CDA79B8" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_NetPeriodicInterestRateCostsOnSwaps" xlink:label="loc_agnc_NetPeriodicInterestRateCostsOnSwaps_E70BB83ED295F1B9DFA820E93CDABFA2" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_agnc_NetPeriodicInterestRateCostsOnSwaps_E70BB83ED295F1B9DFA820E93CDABFA2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentsGainReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion" xlink:label="loc_us-gaap_DerivativeInstrumentsGainReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion_363C62BCDC68578BE90620E93CDAA814" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_us-gaap_DerivativeInstrumentsGainReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion_363C62BCDC68578BE90620E93CDAA814" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge" xlink:label="loc_us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge_42BE0648BF1624D5152B20E93CDAE924" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge_42BE0648BF1624D5152B20E93CDAE924" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeAverageRemainingMaturity1" xlink:label="loc_us-gaap_DerivativeAverageRemainingMaturity1_480907B15B0B7EE3AAC420E93CDB9804" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_us-gaap_DerivativeAverageRemainingMaturity1_480907B15B0B7EE3AAC420E93CDB9804" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DeferredGainLossDiscontinuedInterestRateSwapExpectedToBeReclassifiedFromOciToInterestExpenseNextTwelveMonths" xlink:label="loc_agnc_DeferredGainLossDiscontinuedInterestRateSwapExpectedToBeReclassifiedFromOciToInterestExpenseNextTwelveMonths_0FF4ABF98F4009515EB420E93CDB7E64" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_agnc_DeferredGainLossDiscontinuedInterestRateSwapExpectedToBeReclassifiedFromOciToInterestExpenseNextTwelveMonths_0FF4ABF98F4009515EB420E93CDB7E64" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_UnrealizedGainLossOnSecurities" xlink:label="loc_us-gaap_UnrealizedGainLossOnSecurities_70F3BF1FCCB8E5F1AB3E20E93CDAD6EB" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_us-gaap_UnrealizedGainLossOnSecurities_70F3BF1FCCB8E5F1AB3E20E93CDAD6EB" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration" xlink:label="loc_agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration_0BBAFCD1AD1644AE068C20E93CDA661F" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration_0BBAFCD1AD1644AE068C20E93CDA661F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeLiabilityNotionalAmount" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_CE850D56C91BFC856D5720E93CDA5584" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_CE850D56C91BFC856D5720E93CDA5584" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeAverageFixedInterestRate" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_AAD5639E7588CAFA997520E93CDA4A5F" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_AAD5639E7588CAFA997520E93CDA4A5F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateDerivativesAtFairValueNet" xlink:label="loc_us-gaap_InterestRateDerivativesAtFairValueNet_62DD572F4A941FB1839E20E93CDA8D79" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_us-gaap_InterestRateDerivativesAtFairValueNet_62DD572F4A941FB1839E20E93CDA8D79" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOciIntoIncomeEffectivePortionNetDeDesignatedInterestRateSwaps" xlink:label="loc_agnc_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOciIntoIncomeEffectivePortionNetDeDesignatedInterestRateSwaps_3F9527FC89936BAEC75C20E93CDAFE02" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_agnc_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOciIntoIncomeEffectivePortionNetDeDesignatedInterestRateSwaps_3F9527FC89936BAEC75C20E93CDAFE02" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OptionsAtCost" xlink:label="loc_agnc_OptionsAtCost_C1EDE608E8AA58B4C94620E93CDBB42C" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_agnc_OptionsAtCost_C1EDE608E8AA58B4C94620E93CDBB42C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate" xlink:label="loc_agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate_6E44A790E347E001BB0520E93CDB43CE" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0EEA1E9670DBD434CABA20E93CDAD571" xlink:to="loc_agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate_6E44A790E347E001BB0520E93CDB43CE" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsRemainingInterestRateSwapTermDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_CDD26F98AF6DCD2AA02A20E9933082B8" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_4B83015146E8F271DA4420E99330F292" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_CDD26F98AF6DCD2AA02A20E9933082B8" xlink:to="loc_us-gaap_DerivativeTable_4B83015146E8F271DA4420E99330F292" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativesByMaturityAxis" xlink:label="loc_agnc_DerivativesByMaturityAxis_4090D2402FFB276C27EA20E993307632" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4B83015146E8F271DA4420E99330F292" xlink:to="loc_agnc_DerivativesByMaturityAxis_4090D2402FFB276C27EA20E993307632" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_76298CEEB31859A137BE20E993306444_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativesByMaturityAxis_4090D2402FFB276C27EA20E993307632" xlink:to="loc_agnc_DerivativesByMaturityDomain_76298CEEB31859A137BE20E993306444_default" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_76298CEEB31859A137BE20E993306444" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativesByMaturityAxis_4090D2402FFB276C27EA20E993307632" xlink:to="loc_agnc_DerivativesByMaturityDomain_76298CEEB31859A137BE20E993306444" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_LessThanOrEqualToOneYearMember" xlink:label="loc_agnc_LessThanOrEqualToOneYearMember_51E5B479CACBE1443E7720E99330ABAE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_76298CEEB31859A137BE20E993306444" xlink:to="loc_agnc_LessThanOrEqualToOneYearMember_51E5B479CACBE1443E7720E99330ABAE" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember" xlink:label="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_A91C8AA0E3C932999A0620E993302B73" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_76298CEEB31859A137BE20E993306444" xlink:to="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_A91C8AA0E3C932999A0620E993302B73" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_18E961E0CCBD389195F920E9933018BB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4B83015146E8F271DA4420E99330F292" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_18E961E0CCBD389195F920E9933018BB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2E00C5ACFF4E8E07161F20E993307A1F_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_18E961E0CCBD389195F920E9933018BB" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2E00C5ACFF4E8E07161F20E993307A1F_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2E00C5ACFF4E8E07161F20E993307A1F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_18E961E0CCBD389195F920E9933018BB" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2E00C5ACFF4E8E07161F20E993307A1F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwaptionMember" xlink:label="loc_us-gaap_InterestRateSwaptionMember_EB7B0019CD8996C2E4F420E993304DD4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2E00C5ACFF4E8E07161F20E993307A1F" xlink:to="loc_us-gaap_InterestRateSwaptionMember_EB7B0019CD8996C2E4F420E993304DD4" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ReceiverSwaptionMember" xlink:label="loc_agnc_ReceiverSwaptionMember_289179C158974FE0244B20E993306ADD" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2E00C5ACFF4E8E07161F20E993307A1F" xlink:to="loc_agnc_ReceiverSwaptionMember_289179C158974FE0244B20E993306ADD" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PayerSwaptionMember" xlink:label="loc_agnc_PayerSwaptionMember_31A27DBD6A529AE1FAEC20E99330A2D0" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2E00C5ACFF4E8E07161F20E993307A1F" xlink:to="loc_agnc_PayerSwaptionMember_31A27DBD6A529AE1FAEC20E99330A2D0" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OptionsAtCost" xlink:label="loc_agnc_OptionsAtCost_61F759548849FBC8CEA420E99330C109" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_CDD26F98AF6DCD2AA02A20E9933082B8" xlink:to="loc_agnc_OptionsAtCost_61F759548849FBC8CEA420E99330C109" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateDerivativesAtFairValueNet" xlink:label="loc_us-gaap_InterestRateDerivativesAtFairValueNet_C42D5077C7626A9CCCBC20E99330C05B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_CDD26F98AF6DCD2AA02A20E9933082B8" xlink:to="loc_us-gaap_InterestRateDerivativesAtFairValueNet_C42D5077C7626A9CCCBC20E99330C05B" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration" xlink:label="loc_agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration_B3D1303A47EF27C4024B20E993310EF8" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_CDD26F98AF6DCD2AA02A20E9933082B8" xlink:to="loc_agnc_CashFlowHedgesDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAverageMonthsToExpiration_B3D1303A47EF27C4024B20E993310EF8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeLiabilityNotionalAmount" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_4949D8A2620CBEE21E3720E99330765C" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_CDD26F98AF6DCD2AA02A20E9933082B8" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_4949D8A2620CBEE21E3720E99330765C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeAverageFixedInterestRate" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_5BEF3D78F6B2AB1DF8E620E993300BC7" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_CDD26F98AF6DCD2AA02A20E9933082B8" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_5BEF3D78F6B2AB1DF8E620E993300BC7" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate" xlink:label="loc_agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate_CC841675690DBD28264220E99330CD9F" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_CDD26F98AF6DCD2AA02A20E9933082B8" xlink:to="loc_agnc_InterestRateDerivativeNotDesignatedAsHedgingInstrumentsReceiveRate_CC841675690DBD28264220E99330CD9F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeAverageRemainingMaturity1" xlink:label="loc_us-gaap_DerivativeAverageRemainingMaturity1_F9F6D3F032D1793E3DFF20E993302B69" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_CDD26F98AF6DCD2AA02A20E9933082B8" xlink:to="loc_us-gaap_DerivativeAverageRemainingMaturity1_F9F6D3F032D1793E3DFF20E993302B69" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsSummaryOfOutstandingInterestRateSwapsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_9039B283DC71BEE1B17720E97C6DBE95" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:to="loc_us-gaap_DerivativeTable_9039B283DC71BEE1B17720E97C6DBE95" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativesByMaturityAxis" xlink:label="loc_agnc_DerivativesByMaturityAxis_769A54C10DEC8CCC373320E97C6DD250" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_9039B283DC71BEE1B17720E97C6DBE95" xlink:to="loc_agnc_DerivativesByMaturityAxis_769A54C10DEC8CCC373320E97C6DD250" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativesByMaturityAxis_769A54C10DEC8CCC373320E97C6DD250" xlink:to="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A_default" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativesByMaturityDomain" xlink:label="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativesByMaturityAxis_769A54C10DEC8CCC373320E97C6DD250" xlink:to="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_LessThanOrEqualToOneYearMember" xlink:label="loc_agnc_LessThanOrEqualToOneYearMember_CEE0E9738802D51A08D020E97C6D7A17" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A" xlink:to="loc_agnc_LessThanOrEqualToOneYearMember_CEE0E9738802D51A08D020E97C6D7A17" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember" xlink:label="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_4593299A632B1952127C20E97C6DC448" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A" xlink:to="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_4593299A632B1952127C20E97C6DC448" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember" xlink:label="loc_agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember_BB5EB7069C4A820403C120E97C6D8699" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A" xlink:to="loc_agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember_BB5EB7069C4A820403C120E97C6D8699" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanFiveYearsAndLessThanOrEqualToSevenYearsMember" xlink:label="loc_agnc_GreaterThanFiveYearsAndLessThanOrEqualToSevenYearsMember_54EDA53899316F5D092A20E97C6D005B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A" xlink:to="loc_agnc_GreaterThanFiveYearsAndLessThanOrEqualToSevenYearsMember_54EDA53899316F5D092A20E97C6D005B" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanSevenYearsAndLessThanOrEqualToTenYearsMember" xlink:label="loc_agnc_GreaterThanSevenYearsAndLessThanOrEqualToTenYearsMember_0AE45A7BC4DF2983820A20E97C6DC564" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A" xlink:to="loc_agnc_GreaterThanSevenYearsAndLessThanOrEqualToTenYearsMember_0AE45A7BC4DF2983820A20E97C6DC564" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanTenYearsMember" xlink:label="loc_agnc_GreaterThanTenYearsMember_F4C00972241924396C5720E97C6D3ADE" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativesByMaturityDomain_A11CDEC526647952EB3A20E97C6D0B0A" xlink:to="loc_agnc_GreaterThanTenYearsMember_F4C00972241924396C5720E97C6D3ADE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_3958E831BAB20DB38B6120E97C6D9E21" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_9039B283DC71BEE1B17720E97C6DBE95" xlink:to="loc_us-gaap_DerivativeByNatureAxis_3958E831BAB20DB38B6120E97C6D9E21" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_00797A6FCDACBE3C027C20E97C6DC5D7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_3958E831BAB20DB38B6120E97C6D9E21" xlink:to="loc_us-gaap_DerivativeNameDomain_00797A6FCDACBE3C027C20E97C6DC5D7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_00797A6FCDACBE3C027C20E97C6DC5D7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_3958E831BAB20DB38B6120E97C6D9E21" xlink:to="loc_us-gaap_DerivativeNameDomain_00797A6FCDACBE3C027C20E97C6DC5D7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ForwardContractsMember" xlink:label="loc_us-gaap_ForwardContractsMember_489F09DCABAEFE4766DC20E97C6D0ED8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_00797A6FCDACBE3C027C20E97C6DC5D7" xlink:to="loc_us-gaap_ForwardContractsMember_489F09DCABAEFE4766DC20E97C6D0ED8" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestRateSwapsExcludingForwardStartingMember" xlink:label="loc_agnc_InterestRateSwapsExcludingForwardStartingMember_CF3059E30046BE8797DE20E97C6D7097" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_00797A6FCDACBE3C027C20E97C6DC5D7" xlink:to="loc_agnc_InterestRateSwapsExcludingForwardStartingMember_CF3059E30046BE8797DE20E97C6D7097" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativePositionAxis" xlink:label="loc_agnc_DerivativePositionAxis_0186664272EFE610BC9C20E97C6D4561" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_9039B283DC71BEE1B17720E97C6DBE95" xlink:to="loc_agnc_DerivativePositionAxis_0186664272EFE610BC9C20E97C6D4561" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_46900F7D672309F9748920E97C6DE272_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativePositionAxis_0186664272EFE610BC9C20E97C6D4561" xlink:to="loc_agnc_DerivativePositionDomain_46900F7D672309F9748920E97C6DE272_default" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_46900F7D672309F9748920E97C6DE272" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativePositionAxis_0186664272EFE610BC9C20E97C6D4561" xlink:to="loc_agnc_DerivativePositionDomain_46900F7D672309F9748920E97C6DE272" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_FC48880AC617289D44A720E97C6D01E6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_46900F7D672309F9748920E97C6DE272" xlink:to="loc_us-gaap_InterestRateSwapMember_FC48880AC617289D44A720E97C6D01E6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_EFBFC84E19D234596FDF20E97C6EC9A7" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_9039B283DC71BEE1B17720E97C6DBE95" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_EFBFC84E19D234596FDF20E97C6EC9A7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_BE32216417C70F7C380420E97C6ECE3E_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_EFBFC84E19D234596FDF20E97C6EC9A7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_BE32216417C70F7C380420E97C6ECE3E_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_BE32216417C70F7C380420E97C6ECE3E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_EFBFC84E19D234596FDF20E97C6EC9A7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_BE32216417C70F7C380420E97C6ECE3E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_510AF457E370F587C39620E97C6E1E3A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_BE32216417C70F7C380420E97C6ECE3E" xlink:to="loc_us-gaap_InterestRateSwapMember_510AF457E370F587C39620E97C6E1E3A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeLiabilityNotionalAmount" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_395017C26B7E17AEB81320E97C6E6902" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_395017C26B7E17AEB81320E97C6E6902" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeAverageFixedInterestRate" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_ABE0C363AA610639836420E97C6E8334" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_ABE0C363AA610639836420E97C6E8334" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OptionsAtCost" xlink:label="loc_agnc_OptionsAtCost_B3BA5150F39CAC2A000520E97C6E4670" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:to="loc_agnc_OptionsAtCost_B3BA5150F39CAC2A000520E97C6E4670" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeAverageVariableInterestRate" xlink:label="loc_us-gaap_DerivativeAverageVariableInterestRate_224F0D1249CDE9CA720F20E97C6E237C" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:to="loc_us-gaap_DerivativeAverageVariableInterestRate_224F0D1249CDE9CA720F20E97C6E237C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAtFairValueNet" xlink:label="loc_us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAtFairValueNet_A08910F3927342BF3EB620E97C6EBF61" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:to="loc_us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAtFairValueNet_A08910F3927342BF3EB620E97C6EBF61" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeAverageRemainingMaturity1" xlink:label="loc_us-gaap_DerivativeAverageRemainingMaturity1_96D50E130A52A85C847720E97C6E156E" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:to="loc_us-gaap_DerivativeAverageRemainingMaturity1_96D50E130A52A85C847720E97C6E156E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_A44F5BF7390583EE078B20E97C6E456E" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:to="loc_invest_DerivativeNotionalAmount_A44F5BF7390583EE078B20E97C6E456E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeHigherRemainingMaturityRange1" xlink:label="loc_us-gaap_DerivativeHigherRemainingMaturityRange1_C9A35514AB5C9C1BB85A20E97C6EB3FD" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72FF2C307BCAEB042A6C20E97C6EBB50" xlink:to="loc_us-gaap_DerivativeHigherRemainingMaturityRange1_C9A35514AB5C9C1BB85A20E97C6EB3FD" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsTables" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_DDAB70F11A89C4D202CA20E83ACFAF93" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_12131ED45913EA0DEEED20E83ACFC7FF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_DDAB70F11A89C4D202CA20E83ACFAF93" xlink:to="loc_us-gaap_DerivativeTable_12131ED45913EA0DEEED20E83ACFC7FF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_F5D6A253808B946A7C4120E83ACFCD1F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_12131ED45913EA0DEEED20E83ACFC7FF" xlink:to="loc_us-gaap_HedgingDesignationAxis_F5D6A253808B946A7C4120E83ACFCD1F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_D9B0C0DD312DA0CE45FD20E83ACF63DC_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_F5D6A253808B946A7C4120E83ACFCD1F" xlink:to="loc_us-gaap_HedgingDesignationDomain_D9B0C0DD312DA0CE45FD20E83ACF63DC_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_D9B0C0DD312DA0CE45FD20E83ACF63DC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_F5D6A253808B946A7C4120E83ACFCD1F" xlink:to="loc_us-gaap_HedgingDesignationDomain_D9B0C0DD312DA0CE45FD20E83ACF63DC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NondesignatedMember" xlink:label="loc_us-gaap_NondesignatedMember_4E344D2B028756251AE720E83ACF1EA6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_D9B0C0DD312DA0CE45FD20E83ACF63DC" xlink:to="loc_us-gaap_NondesignatedMember_4E344D2B028756251AE720E83ACF1EA6" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ScheduleOfOutstandingDerivativesNotDesignatedAsHedgingInstrumentsTableTextBlock" xlink:label="loc_agnc_ScheduleOfOutstandingDerivativesNotDesignatedAsHedgingInstrumentsTableTextBlock_ABD67325E028FC5D76F220E83ACF071A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DDAB70F11A89C4D202CA20E83ACFAF93" xlink:to="loc_agnc_ScheduleOfOutstandingDerivativesNotDesignatedAsHedgingInstrumentsTableTextBlock_ABD67325E028FC5D76F220E83ACF071A" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ScheduleOfInterestRateSwapAgreementByRemainingMaturityTableTextBlock" xlink:label="loc_agnc_ScheduleOfInterestRateSwapAgreementByRemainingMaturityTableTextBlock_14D954A42435FCEE92DE20E83ACF201C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DDAB70F11A89C4D202CA20E83ACFAF93" xlink:to="loc_agnc_ScheduleOfInterestRateSwapAgreementByRemainingMaturityTableTextBlock_14D954A42435FCEE92DE20E83ACF201C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ScheduleOfInterestRateSwaptionAgreementsOutstandinTableTextBlock" xlink:label="loc_agnc_ScheduleOfInterestRateSwaptionAgreementsOutstandinTableTextBlock_B729DF3A37E2FA88A78120E83ACF3810" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DDAB70F11A89C4D202CA20E83ACFAF93" xlink:to="loc_agnc_ScheduleOfInterestRateSwaptionAgreementsOutstandinTableTextBlock_B729DF3A37E2FA88A78120E83ACF3810" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_USgovernmentsecuritiesTableTextBlock" xlink:label="loc_agnc_USgovernmentsecuritiesTableTextBlock_1D8B5E3EE3091A97C84420E83ACF4FB9" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DDAB70F11A89C4D202CA20E83ACFAF93" xlink:to="loc_agnc_USgovernmentsecuritiesTableTextBlock_1D8B5E3EE3091A97C84420E83ACF4FB9" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ScheduleOfLongAndShortPositionOfDerivativeInstrumentsTableTextBlock" xlink:label="loc_agnc_ScheduleOfLongAndShortPositionOfDerivativeInstrumentsTableTextBlock_07F46A428EC4EB7D05BF20E83ACF675B" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DDAB70F11A89C4D202CA20E83ACFAF93" xlink:to="loc_agnc_ScheduleOfLongAndShortPositionOfDerivativeInstrumentsTableTextBlock_07F46A428EC4EB7D05BF20E83ACF675B" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ScheduleOfOutstandingNotDesignatedAsHedgingInstrumentsTableTextBlock" xlink:label="loc_agnc_ScheduleOfOutstandingNotDesignatedAsHedgingInstrumentsTableTextBlock_BAB3D1CD76A97588C9DC20E83ACF7AAE" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DDAB70F11A89C4D202CA20E83ACFAF93" xlink:to="loc_agnc_ScheduleOfOutstandingNotDesignatedAsHedgingInstrumentsTableTextBlock_BAB3D1CD76A97588C9DC20E83ACF7AAE" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsTbaSecuritiesByCouponAndIssuerDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_B2B68290F92EE7B73DBB20BA100BA038" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_3DC77F6012E101C1DC8320BA100930FD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_B2B68290F92EE7B73DBB20BA100BA038" xlink:to="loc_us-gaap_DerivativeTable_3DC77F6012E101C1DC8320BA100930FD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativePositionAxis" xlink:label="loc_agnc_DerivativePositionAxis_98E91E22B1F71D05000A20BA10093874" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3DC77F6012E101C1DC8320BA100930FD" xlink:to="loc_agnc_DerivativePositionAxis_98E91E22B1F71D05000A20BA10093874" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_D30F6FE55936B959AA5920BA100930FB_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_agnc_DerivativePositionAxis_98E91E22B1F71D05000A20BA10093874" xlink:to="loc_agnc_DerivativePositionDomain_D30F6FE55936B959AA5920BA100930FB_default" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativePositionDomain" xlink:label="loc_agnc_DerivativePositionDomain_D30F6FE55936B959AA5920BA100930FB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_agnc_DerivativePositionAxis_98E91E22B1F71D05000A20BA10093874" xlink:to="loc_agnc_DerivativePositionDomain_D30F6FE55936B959AA5920BA100930FB" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A2.5CouponMember" xlink:label="loc_agnc_A2.5CouponMember_557F2ACC63461648E04020BA1009CEEB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D30F6FE55936B959AA5920BA100930FB" xlink:to="loc_agnc_A2.5CouponMember_557F2ACC63461648E04020BA1009CEEB" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A3.0CouponMember" xlink:label="loc_agnc_A3.0CouponMember_966194FE01E967CF947920BA1009BA4B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D30F6FE55936B959AA5920BA100930FB" xlink:to="loc_agnc_A3.0CouponMember_966194FE01E967CF947920BA1009BA4B" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A3.5CouponMember" xlink:label="loc_agnc_A3.5CouponMember_4BAA22509B3DF535FD8C20BA1009265D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D30F6FE55936B959AA5920BA100930FB" xlink:to="loc_agnc_A3.5CouponMember_4BAA22509B3DF535FD8C20BA1009265D" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A4.0CouponMember" xlink:label="loc_agnc_A4.0CouponMember_4508F03C234B26D7CF3B20BA100AEEA9" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D30F6FE55936B959AA5920BA100930FB" xlink:to="loc_agnc_A4.0CouponMember_4508F03C234B26D7CF3B20BA100AEEA9" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A4.5CouponMember" xlink:label="loc_agnc_A4.5CouponMember_77C7AD81CD604E0403A920BA100AB513" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_DerivativePositionDomain_D30F6FE55936B959AA5920BA100930FB" xlink:to="loc_agnc_A4.5CouponMember_77C7AD81CD604E0403A920BA100AB513" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_F7FBD2F4E42C273174D620BA100A7FC8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3DC77F6012E101C1DC8320BA100930FD" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_F7FBD2F4E42C273174D620BA100A7FC8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_B30B5E4936C3B803114D20BA100A8CAA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_F7FBD2F4E42C273174D620BA100A7FC8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_B30B5E4936C3B803114D20BA100A8CAA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_B30B5E4936C3B803114D20BA100A8CAA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_F7FBD2F4E42C273174D620BA100A7FC8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_B30B5E4936C3B803114D20BA100A8CAA" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_25A3A2F3C7C9DE9E900720BA100AA643" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_B30B5E4936C3B803114D20BA100A8CAA" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_25A3A2F3C7C9DE9E900720BA100AA643" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_B92F258E7F07ED0A14E320BA100A8673" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3DC77F6012E101C1DC8320BA100930FD" xlink:to="loc_us-gaap_DerivativeByNatureAxis_B92F258E7F07ED0A14E320BA100A8673" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_B81527129BAE132E3AD420BA100ACE73_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_B92F258E7F07ED0A14E320BA100A8673" xlink:to="loc_us-gaap_DerivativeNameDomain_B81527129BAE132E3AD420BA100ACE73_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_B81527129BAE132E3AD420BA100ACE73" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_B92F258E7F07ED0A14E320BA100A8673" xlink:to="loc_us-gaap_DerivativeNameDomain_B81527129BAE132E3AD420BA100ACE73" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A15YearMaturityMember" xlink:label="loc_agnc_A15YearMaturityMember_F61BA68332933D83C07120BA100BCF21" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_B81527129BAE132E3AD420BA100ACE73" xlink:to="loc_agnc_A15YearMaturityMember_F61BA68332933D83C07120BA100BCF21" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A30YearMaturityMember" xlink:label="loc_agnc_A30YearMaturityMember_0DECEF08FEA963D7D0EE20BA100B816B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_B81527129BAE132E3AD420BA100ACE73" xlink:to="loc_agnc_A30YearMaturityMember_0DECEF08FEA963D7D0EE20BA100B816B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember" xlink:label="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_28B93659CC9C5B04871A20BA100B4CF7" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_B81527129BAE132E3AD420BA100ACE73" xlink:to="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_28B93659CC9C5B04871A20BA100B4CF7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember" xlink:label="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_8154DBE73CBD86697E3320BA100B7E6E" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_B81527129BAE132E3AD420BA100ACE73" xlink:to="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_8154DBE73CBD86697E3320BA100B7E6E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember" xlink:label="loc_us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember_6FF26FA2ECAA4B9A1C1820BA100B221F" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_B81527129BAE132E3AD420BA100ACE73" xlink:to="loc_us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember_6FF26FA2ECAA4B9A1C1820BA100B221F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_4F4B7B20C5FE3B66DA4D20BA100B8B4F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_B2B68290F92EE7B73DBB20BA100BA038" xlink:to="loc_invest_DerivativeNotionalAmount_4F4B7B20C5FE3B66DA4D20BA100B8B4F" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DerivativeForwardSettlementValue" xlink:label="loc_agnc_DerivativeForwardSettlementValue_6CC9E008091A7182FEBD20BA100BF20C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_B2B68290F92EE7B73DBB20BA100BA038" xlink:to="loc_agnc_DerivativeForwardSettlementValue_6CC9E008091A7182FEBD20BA100BF20C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_2437E3ACB1CC225E0D9C20BA100BAA30" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_B2B68290F92EE7B73DBB20BA100BA038" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_2437E3ACB1CC225E0D9C20BA100BAA30" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_5886487FBFA11A831C5B20BA100B619A" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_B2B68290F92EE7B73DBB20BA100BA038" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_5886487FBFA11A831C5B20BA100B619A" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DerivativeAndOtherHedgingInstrumentsUsTreasurySecuritiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_C7AAEF5A91BA5626661120BA1021C9B1" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_41AD71221835C88E891120BA101F486F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_C7AAEF5A91BA5626661120BA1021C9B1" xlink:to="loc_us-gaap_DerivativeTable_41AD71221835C88E891120BA101F486F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_0ED17E94C79269AD4B6420BA10202621" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_41AD71221835C88E891120BA101F486F" xlink:to="loc_us-gaap_DerivativeByNatureAxis_0ED17E94C79269AD4B6420BA10202621" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_F992CE7780EF98A76AE920BA1020F071_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_0ED17E94C79269AD4B6420BA10202621" xlink:to="loc_us-gaap_DerivativeNameDomain_F992CE7780EF98A76AE920BA1020F071_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_F992CE7780EF98A76AE920BA1020F071" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_0ED17E94C79269AD4B6420BA10202621" xlink:to="loc_us-gaap_DerivativeNameDomain_F992CE7780EF98A76AE920BA1020F071" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AtParValueMember" xlink:label="loc_agnc_AtParValueMember_72FAC339CA06ABEC8AE620BA1020704E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_F992CE7780EF98A76AE920BA1020F071" xlink:to="loc_agnc_AtParValueMember_72FAC339CA06ABEC8AE620BA1020704E" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AtCostBasisMember" xlink:label="loc_agnc_AtCostBasisMember_E1AB31808610FB39CAAC20BA1020ACE3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_F992CE7780EF98A76AE920BA1020F071" xlink:to="loc_agnc_AtCostBasisMember_E1AB31808610FB39CAAC20BA1020ACE3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_78AC908785B9656CBF4320BA10201A72" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_41AD71221835C88E891120BA101F486F" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_78AC908785B9656CBF4320BA10201A72" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_88E3E6D0C7DF61BDBB6220BA10205DE0_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_78AC908785B9656CBF4320BA10201A72" xlink:to="loc_us-gaap_HedgingRelationshipDomain_88E3E6D0C7DF61BDBB6220BA10205DE0_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_88E3E6D0C7DF61BDBB6220BA10205DE0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_78AC908785B9656CBF4320BA10201A72" xlink:to="loc_us-gaap_HedgingRelationshipDomain_88E3E6D0C7DF61BDBB6220BA10205DE0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueHedgingMember" xlink:label="loc_us-gaap_FairValueHedgingMember_4B26569780224FD8395920BA1020D6A8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_88E3E6D0C7DF61BDBB6220BA10205DE0" xlink:to="loc_us-gaap_FairValueHedgingMember_4B26569780224FD8395920BA1020D6A8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_79B91059E236C347653320BA1020ED1E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_41AD71221835C88E891120BA101F486F" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_79B91059E236C347653320BA1020ED1E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_1DAB17FFC44E3CD1167520BA1020DA15_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_79B91059E236C347653320BA1020ED1E" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_1DAB17FFC44E3CD1167520BA1020DA15_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_1DAB17FFC44E3CD1167520BA1020DA15" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_79B91059E236C347653320BA1020ED1E" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_1DAB17FFC44E3CD1167520BA1020DA15" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A3YearMaturityMemberMember" xlink:label="loc_agnc_A3YearMaturityMemberMember_1DB34FBE87BB7B21350A20BA102035CD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_1DAB17FFC44E3CD1167520BA1020DA15" xlink:to="loc_agnc_A3YearMaturityMemberMember_1DB34FBE87BB7B21350A20BA102035CD" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A5YearMaturityMember" xlink:label="loc_agnc_A5YearMaturityMember_3746CBD410CBA6D8FBD820BA1020294F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_1DAB17FFC44E3CD1167520BA1020DA15" xlink:to="loc_agnc_A5YearMaturityMember_3746CBD410CBA6D8FBD820BA1020294F" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A7YearsMaturityMember" xlink:label="loc_agnc_A7YearsMaturityMember_7189982D3455CC03FBB320BA1020EE48" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_1DAB17FFC44E3CD1167520BA1020DA15" xlink:to="loc_agnc_A7YearsMaturityMember_7189982D3455CC03FBB320BA1020EE48" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A10YearMaturityMember" xlink:label="loc_agnc_A10YearMaturityMember_BE5337ACC62FCCD1F40020BA10208B52" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_1DAB17FFC44E3CD1167520BA1020DA15" xlink:to="loc_agnc_A10YearMaturityMember_BE5337ACC62FCCD1F40020BA10208B52" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_Governmentbondsownedandsoldshortnet" xlink:label="loc_agnc_Governmentbondsownedandsoldshortnet_8882B94C90CD0314014020BA10215B95" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_C7AAEF5A91BA5626661120BA1021C9B1" xlink:to="loc_agnc_Governmentbondsownedandsoldshortnet_8882B94C90CD0314014020BA10215B95" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/FairValueMeasurements" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/FairValueMeasurementsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_291E294560FF7D32CA7320BDBA9255B1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_291E294560FF7D32CA7320BDBA9255B1" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_45252A5A6628A839862C20BDBA925BF9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_291E294560FF7D32CA7320BDBA9255B1" xlink:to="loc_us-gaap_DerivativeByNatureAxis_45252A5A6628A839862C20BDBA925BF9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_153DF9406E39ED2251F220BDBA923DD8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_45252A5A6628A839862C20BDBA925BF9" xlink:to="loc_us-gaap_DerivativeNameDomain_153DF9406E39ED2251F220BDBA923DD8_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_153DF9406E39ED2251F220BDBA923DD8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_45252A5A6628A839862C20BDBA925BF9" xlink:to="loc_us-gaap_DerivativeNameDomain_153DF9406E39ED2251F220BDBA923DD8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_C5D5A248C92F209E7F2F20BDBA924F37" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_153DF9406E39ED2251F220BDBA923DD8" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_C5D5A248C92F209E7F2F20BDBA924F37" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_3DFDC928D5314A056FBF20BDBA92806E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_291E294560FF7D32CA7320BDBA9255B1" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_3DFDC928D5314A056FBF20BDBA92806E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_D5CCB094FABA3639E2F620BDBA92B4E4_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_3DFDC928D5314A056FBF20BDBA92806E" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_D5CCB094FABA3639E2F620BDBA92B4E4_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_D5CCB094FABA3639E2F620BDBA92B4E4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_3DFDC928D5314A056FBF20BDBA92806E" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_D5CCB094FABA3639E2F620BDBA92B4E4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_5C7FF0564BD2CB43646D20BDBA92C465" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_D5CCB094FABA3639E2F620BDBA92B4E4" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_5C7FF0564BD2CB43646D20BDBA92C465" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwaptionMember" xlink:label="loc_us-gaap_InterestRateSwaptionMember_7325316B0677AFA671C520BDBA92F375" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_D5CCB094FABA3639E2F620BDBA92B4E4" xlink:to="loc_us-gaap_InterestRateSwaptionMember_7325316B0677AFA671C520BDBA92F375" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_9A80CFC06F678E69A70020BDBA925121" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_D5CCB094FABA3639E2F620BDBA92B4E4" xlink:to="loc_us-gaap_InterestRateSwapMember_9A80CFC06F678E69A70020BDBA925121" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FutureMember" xlink:label="loc_us-gaap_FutureMember_F070854EEF4FD0A4576820BDBA931BEB" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_D5CCB094FABA3639E2F620BDBA92B4E4" xlink:to="loc_us-gaap_FutureMember_F070854EEF4FD0A4576820BDBA931BEB" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_C9B371424B3C7739921320BDBA932789" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_D5CCB094FABA3639E2F620BDBA92B4E4" xlink:to="loc_agnc_PurchasesOfTbasAndForwardSettlingAgencySecuritiesMember_C9B371424B3C7739921320BDBA932789" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_9A8ABF25DF058157298B20BDBA93749F" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_291E294560FF7D32CA7320BDBA9255B1" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_9A8ABF25DF058157298B20BDBA93749F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_14507911FBE902C1D42520BDBA9397FD_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_9A8ABF25DF058157298B20BDBA93749F" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_14507911FBE902C1D42520BDBA9397FD_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_14507911FBE902C1D42520BDBA9397FD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_9A8ABF25DF058157298B20BDBA93749F" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_14507911FBE902C1D42520BDBA9397FD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember" xlink:label="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_989F81ACDB4C9031195F20BDBA938321" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_14507911FBE902C1D42520BDBA9397FD" xlink:to="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_989F81ACDB4C9031195F20BDBA938321" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_FFEB0A0B5A36357C4EE220BDBA93A5F7" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_291E294560FF7D32CA7320BDBA9255B1" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_FFEB0A0B5A36357C4EE220BDBA93A5F7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_6338CF1A933DDA40D1E020BDBA9318EB_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_FFEB0A0B5A36357C4EE220BDBA93A5F7" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_6338CF1A933DDA40D1E020BDBA9318EB_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_6338CF1A933DDA40D1E020BDBA9318EB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_FFEB0A0B5A36357C4EE220BDBA93A5F7" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_6338CF1A933DDA40D1E020BDBA9318EB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_9A6A29061B227886459520BDBA93991A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_6338CF1A933DDA40D1E020BDBA9318EB" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_9A6A29061B227886459520BDBA93991A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_25759B645BB6519ACC8220BDBA934CE8" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_291E294560FF7D32CA7320BDBA9255B1" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_25759B645BB6519ACC8220BDBA934CE8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5B6C96F1B26941A7DBE720BDBA9316B8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_25759B645BB6519ACC8220BDBA934CE8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5B6C96F1B26941A7DBE720BDBA9316B8_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5B6C96F1B26941A7DBE720BDBA9316B8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_25759B645BB6519ACC8220BDBA934CE8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5B6C96F1B26941A7DBE720BDBA9316B8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_7EF5029C989AABE867B820BDBA936833" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5B6C96F1B26941A7DBE720BDBA9316B8" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_7EF5029C989AABE867B820BDBA936833" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_3ABB7E553370F5C936EB20BDBA938690" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5B6C96F1B26941A7DBE720BDBA9316B8" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_3ABB7E553370F5C936EB20BDBA938690" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_6DC69A35B39427C1FF9F20BDBA933BB4" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_291E294560FF7D32CA7320BDBA9255B1" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_6DC69A35B39427C1FF9F20BDBA933BB4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1D32ADCB7CD46D5CEE4420BDBA9335C4_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_6DC69A35B39427C1FF9F20BDBA933BB4" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1D32ADCB7CD46D5CEE4420BDBA9335C4_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1D32ADCB7CD46D5CEE4420BDBA9335C4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_6DC69A35B39427C1FF9F20BDBA933BB4" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1D32ADCB7CD46D5CEE4420BDBA9335C4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_0C508FC42C0A59B85D8A20BDBA93CD40" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1D32ADCB7CD46D5CEE4420BDBA9335C4" xlink:to="loc_us-gaap_InterestRateSwapMember_0C508FC42C0A59B85D8A20BDBA93CD40" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TBAandForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_4A587E800BAA2593B80E20BDBA93FD70" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1D32ADCB7CD46D5CEE4420BDBA9335C4" xlink:to="loc_agnc_TBAandForwardSettlingAgencySecuritiesMember_4A587E800BAA2593B80E20BDBA93FD70" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_SaleOfTbaAndForwardSettlingAgencySecuritiesMember" xlink:label="loc_agnc_SaleOfTbaAndForwardSettlingAgencySecuritiesMember_C434972102CF33BA9D5720BDBA935C1F" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1D32ADCB7CD46D5CEE4420BDBA9335C4" xlink:to="loc_agnc_SaleOfTbaAndForwardSettlingAgencySecuritiesMember_C434972102CF33BA9D5720BDBA935C1F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_88BA32A0C9F2C731CC7720BDBA93F5E3" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_1D32ADCB7CD46D5CEE4420BDBA9335C4" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_88BA32A0C9F2C731CC7720BDBA93F5E3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_A671CD8FDC9E5D32A99B20BDBA9331B1" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_291E294560FF7D32CA7320BDBA9255B1" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_A671CD8FDC9E5D32A99B20BDBA9331B1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_CFE8CA98735E7DE8FB5820BDBA938DA2_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_A671CD8FDC9E5D32A99B20BDBA9331B1" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_CFE8CA98735E7DE8FB5820BDBA938DA2_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_CFE8CA98735E7DE8FB5820BDBA938DA2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_A671CD8FDC9E5D32A99B20BDBA9331B1" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_CFE8CA98735E7DE8FB5820BDBA938DA2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_DE714B6ED34F14F1072120BDBA93997F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_CFE8CA98735E7DE8FB5820BDBA938DA2" xlink:to="loc_us-gaap_InterestRateSwapMember_DE714B6ED34F14F1072120BDBA93997F" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TransfersBetweenHierarchyLevels" xlink:label="loc_agnc_TransfersBetweenHierarchyLevels_C33A0BA6A7E95F205F1D20BDBA941C43" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_agnc_TransfersBetweenHierarchyLevels_C33A0BA6A7E95F205F1D20BDBA941C43" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FinancialInstrumentsOwnedMortgagesMortgageBackedAndAssetBackedSecuritiesAtFairValue" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedMortgagesMortgageBackedAndAssetBackedSecuritiesAtFairValue_116B5B2B142C2C9AC47320BDBA9331BA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedMortgagesMortgageBackedAndAssetBackedSecuritiesAtFairValue_116B5B2B142C2C9AC47320BDBA9331BA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets" xlink:label="loc_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_685399516E730AD2B99D20BDBA93EEF4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_685399516E730AD2B99D20BDBA93EEF4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_FA157A52268096899CC620BDBA938790" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_FA157A52268096899CC620BDBA938790" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeAssets" xlink:label="loc_us-gaap_DerivativeAssets_A153DBEB1952736D13B820BDBA94B7EC" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_DerivativeAssets_A153DBEB1952736D13B820BDBA94B7EC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_F77F9F24F5EA12E23B9E20BDBA94A1E8" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_F77F9F24F5EA12E23B9E20BDBA94A1E8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherLongTermDebt" xlink:label="loc_us-gaap_OtherLongTermDebt_98139B47CCFF3D19AAD420BDBA943E93" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_OtherLongTermDebt_98139B47CCFF3D19AAD420BDBA943E93" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue" xlink:label="loc_agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue_B5BA422D11A5EE3AE90920BDBA9434B5" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue_B5BA422D11A5EE3AE90920BDBA9434B5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_3E50FFA4DF8AA5DA9E9E20BDBA94F773" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_3E50FFA4DF8AA5DA9E9E20BDBA94F773" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MarketableSecuritiesEquitySecurities" xlink:label="loc_us-gaap_MarketableSecuritiesEquitySecurities_58BA6A2FE8B5FC72CA2E20BDBA947A1D" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_MarketableSecuritiesEquitySecurities_58BA6A2FE8B5FC72CA2E20BDBA947A1D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_8907D427098D9773D42720BDBA949AD8" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_8907D427098D9773D42720BDBA949AD8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_4B190D23024D1D3821AA20BDBA94145F" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_06DC795A963B4BCC4B2920BDBA932306" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_4B190D23024D1D3821AA20BDBA94145F" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/InterimConsolidatedFinancialStatements" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecurities" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesComponentsOfInvestmentSecuritiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfInvestmentsLineItems" xlink:label="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfInvestmentsTable" xlink:label="loc_us-gaap_ScheduleOfInvestmentsTable_DD48D740754D75EF04992095D271DB33" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_us-gaap_ScheduleOfInvestmentsTable_DD48D740754D75EF04992095D271DB33" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_3A15273FF8EE46A4D7962095D271D89C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfInvestmentsTable_DD48D740754D75EF04992095D271DB33" xlink:to="loc_us-gaap_InvestmentTypeAxis_3A15273FF8EE46A4D7962095D271D89C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_E9A7686C231D6B8A932C2095D271A769_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_3A15273FF8EE46A4D7962095D271D89C" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_E9A7686C231D6B8A932C2095D271A769_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_E9A7686C231D6B8A932C2095D271A769" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_3A15273FF8EE46A4D7962095D271D89C" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_E9A7686C231D6B8A932C2095D271A769" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember" xlink:label="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_3FBE74120D79AE32BDE52095D2719F1B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_E9A7686C231D6B8A932C2095D271A769" xlink:to="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_3FBE74120D79AE32BDE52095D2719F1B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember" xlink:label="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_167DCDF6F339394665362095D276B6C9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_E9A7686C231D6B8A932C2095D271A769" xlink:to="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_167DCDF6F339394665362095D276B6C9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember" xlink:label="loc_us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember_66EB34BA01CF7F91E9482095D276C37A" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_E9A7686C231D6B8A932C2095D271A769" xlink:to="loc_us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember_66EB34BA01CF7F91E9482095D276C37A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EligibleItemOrGroupForFairValueOptionAxis" xlink:label="loc_us-gaap_EligibleItemOrGroupForFairValueOptionAxis_3F6D02966F9F62F2D0FA2095D2763BDC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfInvestmentsTable_DD48D740754D75EF04992095D271DB33" xlink:to="loc_us-gaap_EligibleItemOrGroupForFairValueOptionAxis_3F6D02966F9F62F2D0FA2095D2763BDC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueOptionEligibleItemOrGroupDomain" xlink:label="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_E33ACD6BA39D9431B0942095D27693DA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EligibleItemOrGroupForFairValueOptionAxis_3F6D02966F9F62F2D0FA2095D2763BDC" xlink:to="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_E33ACD6BA39D9431B0942095D27693DA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueOptionEligibleItemOrGroupDomain" xlink:label="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_E33ACD6BA39D9431B0942095D27693DA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EligibleItemOrGroupForFairValueOptionAxis_3F6D02966F9F62F2D0FA2095D2763BDC" xlink:to="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_E33ACD6BA39D9431B0942095D27693DA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableforsaleSecuritiesMember" xlink:label="loc_us-gaap_AvailableforsaleSecuritiesMember_53B1CEA79311729C85542095D2764301" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_E33ACD6BA39D9431B0942095D27693DA" xlink:to="loc_us-gaap_AvailableforsaleSecuritiesMember_53B1CEA79311729C85542095D2764301" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AgencySecuritiesRemeasuredAtFairValueThroughEarningsMember" xlink:label="loc_agnc_AgencySecuritiesRemeasuredAtFairValueThroughEarningsMember_A100D29436B9F951A3A22095D27687DF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionEligibleItemOrGroupDomain_E33ACD6BA39D9431B0942095D27693DA" xlink:to="loc_agnc_AgencySecuritiesRemeasuredAtFairValueThroughEarningsMember_A100D29436B9F951A3A22095D27687DF" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AvailableForSaleSecuritiesPar" xlink:label="loc_agnc_AvailableForSaleSecuritiesPar_B8C19101D6E9B539A3CD2095D2765404" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_AvailableForSaleSecuritiesPar_B8C19101D6E9B539A3CD2095D2765404" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_0C24275F0E24ED5F03F72095D2764C8B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_0C24275F0E24ED5F03F72095D2764C8B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentUnamortizedPremium" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedPremium_C350C94B44022E8346642095D276C19A" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedPremium_C350C94B44022E8346642095D276C19A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAmortizedCost" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_8FC75FC7611D3A69300D2095D276121F" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_8FC75FC7611D3A69300D2095D276121F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesGrossUnrealizedGains" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesGrossUnrealizedGains_3A5F1D758EB57233CB922095D27730FC" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesGrossUnrealizedGains_3A5F1D758EB57233CB922095D27730FC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLoss" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLoss_AFB0ED9F26B9D8E2C1CB2095D277D3F6" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLoss_AFB0ED9F26B9D8E2C1CB2095D277D3F6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_1E37DFADB052DB8B3B2B2095D2773B09" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_1E37DFADB052DB8B3B2B2095D2773B09" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestRateDerivativeAssetsAtAmortizedCost" xlink:label="loc_agnc_InterestRateDerivativeAssetsAtAmortizedCost_53B38602E8C241BCC3D32095D2772B4D" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_InterestRateDerivativeAssetsAtAmortizedCost_53B38602E8C241BCC3D32095D2772B4D" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_UnrealizedGainOnDerivatives" xlink:label="loc_agnc_UnrealizedGainOnDerivatives_297A3F725E7A789C32DD2095D2779E8E" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_UnrealizedGainOnDerivatives_297A3F725E7A789C32DD2095D2779E8E" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_UnrealizedLossOnDerivatives" xlink:label="loc_agnc_UnrealizedLossOnDerivatives_B6D234C6D0B3714F899C2095D2774734" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_UnrealizedLossOnDerivatives_B6D234C6D0B3714F899C2095D2774734" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateDerivativeAssetsAtFairValue" xlink:label="loc_us-gaap_InterestRateDerivativeAssetsAtFairValue_80D89A9FEECEEE1DE22C2095D2779C0A" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_us-gaap_InterestRateDerivativeAssetsAtFairValue_80D89A9FEECEEE1DE22C2095D2779C0A" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TotalAgencySecurities" xlink:label="loc_agnc_TotalAgencySecurities_E168402CB1404237EB092095D277FCF0" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_TotalAgencySecurities_E168402CB1404237EB092095D277FCF0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtWeightedAverageInterestRate" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_F10FF26832D8796CFA262095D277860C" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_F10FF26832D8796CFA262095D277860C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_WeightedAverageYieldPercentage" xlink:label="loc_agnc_WeightedAverageYieldPercentage_22548150B0AFE9720FD02095D2772CDA" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_WeightedAverageYieldPercentage_22548150B0AFE9720FD02095D2772CDA" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_WeightedAverageYieldPercentageForPeriod" xlink:label="loc_agnc_WeightedAverageYieldPercentageForPeriod_BAEFB69454FE1F999C582095D2774002" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_WeightedAverageYieldPercentageForPeriod_BAEFB69454FE1F999C582095D2774002" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_UnamortizedPrincipalBalanceOfInterestOnlyStrips" xlink:label="loc_agnc_UnamortizedPrincipalBalanceOfInterestOnlyStrips_FDB62EB5E61AF33D42162095D277F82F" xlink:type="locator" />
    <definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_UnamortizedPrincipalBalanceOfInterestOnlyStrips_FDB62EB5E61AF33D42162095D277F82F" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_WeightedAverageContractualInterestRateOfInterestOnlyStrips" xlink:label="loc_agnc_WeightedAverageContractualInterestRateOfInterestOnlyStrips_60B26213F6B4F230B2FD2095D2774E5A" xlink:type="locator" />
    <definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_WeightedAverageContractualInterestRateOfInterestOnlyStrips_60B26213F6B4F230B2FD2095D2774E5A" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_UnamortizedPrincipalBalanceOfPrincipalOnlyStrips" xlink:label="loc_agnc_UnamortizedPrincipalBalanceOfPrincipalOnlyStrips_E328045A83558DBD102F2095D277C5E1" xlink:type="locator" />
    <definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_UnamortizedPrincipalBalanceOfPrincipalOnlyStrips_E328045A83558DBD102F2095D277C5E1" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio" xlink:label="loc_agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio_265E170D134D039CE75B2095D2776E70" xlink:type="locator" />
    <definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfInvestmentsLineItems_7C278AAA5B269FEB43372095D2761A3E" xlink:to="loc_agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio_265E170D134D039CE75B2095D2776E70" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1B46A8AD8121CCFE7E3C20BA10EDD40A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1B46A8AD8121CCFE7E3C20BA10EDD40A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_7E9ED6DAAB17469254C020BA10EDB81A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1B46A8AD8121CCFE7E3C20BA10EDD40A" xlink:to="loc_us-gaap_DerivativeByNatureAxis_7E9ED6DAAB17469254C020BA10EDB81A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_7E1C4A3CFC0506186FBA20BA10EE3023_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_7E9ED6DAAB17469254C020BA10EDB81A" xlink:to="loc_us-gaap_DerivativeNameDomain_7E1C4A3CFC0506186FBA20BA10EE3023_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_7E1C4A3CFC0506186FBA20BA10EE3023" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_7E9ED6DAAB17469254C020BA10EDB81A" xlink:to="loc_us-gaap_DerivativeNameDomain_7E1C4A3CFC0506186FBA20BA10EE3023" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TbaSecuritiesFifteenYearAndThirtyYearSecuritiesMember" xlink:label="loc_agnc_TbaSecuritiesFifteenYearAndThirtyYearSecuritiesMember_06564B58942C3259E2EE20BA10EEFC94" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_7E1C4A3CFC0506186FBA20BA10EE3023" xlink:to="loc_agnc_TbaSecuritiesFifteenYearAndThirtyYearSecuritiesMember_06564B58942C3259E2EE20BA10EEFC94" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_0EE6875B5DE753F04B9820BA10EED74A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1B46A8AD8121CCFE7E3C20BA10EDD40A" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_0EE6875B5DE753F04B9820BA10EED74A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_6092509A855D070968D820BA10EE0028_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_0EE6875B5DE753F04B9820BA10EED74A" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_6092509A855D070968D820BA10EE0028_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_6092509A855D070968D820BA10EE0028" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_0EE6875B5DE753F04B9820BA10EED74A" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_6092509A855D070968D820BA10EE0028" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_0A83104CCBE8CFEC023820BA10EE5718" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_6092509A855D070968D820BA10EE0028" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_0A83104CCBE8CFEC023820BA10EE5718" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_8A5CB71CD8600D3D917520BA10EEF3E8" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_1B46A8AD8121CCFE7E3C20BA10EDD40A" xlink:to="loc_us-gaap_InvestmentTypeAxis_8A5CB71CD8600D3D917520BA10EEF3E8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_4D623F686FD3C523045720BA10EE42AA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_8A5CB71CD8600D3D917520BA10EEF3E8" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_4D623F686FD3C523045720BA10EE42AA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_4D623F686FD3C523045720BA10EE42AA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_8A5CB71CD8600D3D917520BA10EEF3E8" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_4D623F686FD3C523045720BA10EE42AA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_D4C9675E5DCB8647529020BA10EEC373" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_4D623F686FD3C523045720BA10EE42AA" xlink:to="loc_us-gaap_AgencySecuritiesMember_D4C9675E5DCB8647529020BA10EEC373" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TotalAgencySecurities" xlink:label="loc_agnc_TotalAgencySecurities_F3030B0AAC7F3BE9184420BA10EE9CC0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_agnc_TotalAgencySecurities_F3030B0AAC7F3BE9184420BA10EE9CC0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_E4897A5467A2011F3F3620BA10EEFBE2" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_E4897A5467A2011F3F3620BA10EEFBE2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_CB86C8FA4D16BEF03B4520BA10EE14FF" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_CB86C8FA4D16BEF03B4520BA10EE14FF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_DA333FC7443035D347EF20BA10EFD398" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_DA333FC7443035D347EF20BA10EFD398" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio" xlink:label="loc_agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio_4D18C2A6EDEA2742D7C920BA10EFF59C" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_agnc_FuturePrepaymentRateAssumptionOfInvestmentPortfolio_4D18C2A6EDEA2742D7C920BA10EFF59C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_WeightedAverageLifeInterestOnlySecurities" xlink:label="loc_agnc_WeightedAverageLifeInterestOnlySecurities_950621DE062215AB589E20BA10EFBA52" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_agnc_WeightedAverageLifeInterestOnlySecurities_950621DE062215AB589E20BA10EFBA52" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_WeightedAverageLifePrincipalOnlySecurities" xlink:label="loc_agnc_WeightedAverageLifePrincipalOnlySecurities_A7BA3459DDA5E81DD3C120BA10EF0A2B" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_agnc_WeightedAverageLifePrincipalOnlySecurities_A7BA3459DDA5E81DD3C120BA10EF0A2B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_UnrealizedGainLossOnSecurities" xlink:label="loc_us-gaap_UnrealizedGainLossOnSecurities_92B9A92371AF1E1CF4F920BA10EF710A" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_us-gaap_UnrealizedGainLossOnSecurities_92B9A92371AF1E1CF4F920BA10EF710A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SecuritiesHeldAsCollateralAtFairValue" xlink:label="loc_us-gaap_SecuritiesHeldAsCollateralAtFairValue_0221ADEFD64A8FDA783D20BA10EF7DA2" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_us-gaap_SecuritiesHeldAsCollateralAtFairValue_0221ADEFD64A8FDA783D20BA10EF7DA2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherLongTermDebt" xlink:label="loc_us-gaap_OtherLongTermDebt_99981B0EDD1F6D89003520BA10EF80A0" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_us-gaap_OtherLongTermDebt_99981B0EDD1F6D89003520BA10EF80A0" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PrincipalBalanceOfSecuritiesHeldAsCollateral" xlink:label="loc_agnc_PrincipalBalanceOfSecuritiesHeldAsCollateral_291EE51C51FF986E9A4A20BA10EFF184" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_agnc_PrincipalBalanceOfSecuritiesHeldAsCollateral_291EE51C51FF986E9A4A20BA10EFF184" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_E1B21658293720F6F41920BA10EFD972" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_E1B21658293720F6F41920BA10EFD972" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GainLossOnOtherDebt" xlink:label="loc_agnc_GainLossOnOtherDebt_B7A2442A5E778EA6E0F620BA10EFC704" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_agnc_GainLossOnOtherDebt_B7A2442A5E778EA6E0F620BA10EFC704" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_FairValueOfCmoSecuritiesDirectlyHeld" xlink:label="loc_agnc_FairValueOfCmoSecuritiesDirectlyHeld_1B0A28000CB396C2189A20BA10EF0E68" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_agnc_FairValueOfCmoSecuritiesDirectlyHeld_1B0A28000CB396C2189A20BA10EF0E68" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_SecuritizedCmoSecurities" xlink:label="loc_agnc_SecuritizedCmoSecurities_A252C812FA298742880B20BA10EF1857" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_agnc_SecuritizedCmoSecurities_A252C812FA298742880B20BA10EF1857" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_CmoAndInterestOnlyPricincipalOnlySecuritiesMaximumLossExposure" xlink:label="loc_agnc_CmoAndInterestOnlyPricincipalOnlySecuritiesMaximumLossExposure_F1DBFC896ACD02166D8520BA10EFE1D2" xlink:type="locator" />
    <definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_BE07170DD5012F1B764520BA10EEA1AD" xlink:to="loc_agnc_CmoAndInterestOnlyPricincipalOnlySecuritiesMaximumLossExposure_F1DBFC896ACD02166D8520BA10EFE1D2" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfAgencySecuritiesEstimatedWeightedAverageLifeClassificationsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_643159BB475F5BD03157209678DD68C6" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_3019253F3D32B52E5CBC209678DD9DCA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_643159BB475F5BD03157209678DD68C6" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_3019253F3D32B52E5CBC209678DD9DCA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_759AC8653E090F3CDA57209678DD9879" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_3019253F3D32B52E5CBC209678DD9DCA" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_759AC8653E090F3CDA57209678DD9879" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_B06AF52473C11B3B7DA0209678DD582C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_759AC8653E090F3CDA57209678DD9879" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_B06AF52473C11B3B7DA0209678DD582C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_B06AF52473C11B3B7DA0209678DD582C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_759AC8653E090F3CDA57209678DD9879" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_B06AF52473C11B3B7DA0209678DD582C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember" xlink:label="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_BC588AA50AAE99F25623209678DD69C6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_B06AF52473C11B3B7DA0209678DD582C" xlink:to="loc_agnc_GreaterThanOneYearAndLessThanOrEqualToThreeYearsMember_BC588AA50AAE99F25623209678DD69C6" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember" xlink:label="loc_agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember_AFC728D8332A3D4FD90D209678DD57C4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_B06AF52473C11B3B7DA0209678DD582C" xlink:to="loc_agnc_GreaterThanThreeYearsAndLessThanOrEqualToFiveYearsMember_AFC728D8332A3D4FD90D209678DD57C4" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanFiveYearsMember" xlink:label="loc_agnc_GreaterThanFiveYearsMember_2561D91E8D1C1F96E2E4209678DDE34E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_B06AF52473C11B3B7DA0209678DD582C" xlink:to="loc_agnc_GreaterThanFiveYearsMember_2561D91E8D1C1F96E2E4209678DDE34E" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GreaterThanTenYearsMember" xlink:label="loc_agnc_GreaterThanTenYearsMember_7D86CC2ABEB648943C19209678DD301C" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_B06AF52473C11B3B7DA0209678DD582C" xlink:to="loc_agnc_GreaterThanTenYearsMember_7D86CC2ABEB648943C19209678DD301C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue" xlink:label="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue_1061461ED57A683D718B209678DD5C46" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_643159BB475F5BD03157209678DD68C6" xlink:to="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeFairValue_1061461ED57A683D718B209678DD5C46" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost" xlink:label="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost_7B41B8CEA7BF385D4BF8209678DDC6C4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_643159BB475F5BD03157209678DD68C6" xlink:to="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeAmortizedCost_7B41B8CEA7BF385D4BF8209678DDC6C4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_37A4FC84EE70347ED2C6209678DD0B6D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_643159BB475F5BD03157209678DD68C6" xlink:to="loc_us-gaap_AvailableForSaleSecurities_37A4FC84EE70347ED2C6209678DD0B6D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAmortizedCost" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_6CE3AB5EBBEB782FBC5A209678DD896B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_643159BB475F5BD03157209678DD68C6" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_6CE3AB5EBBEB782FBC5A209678DD896B" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AvailableForSaleSecuritiesWeightedAverageLifeCouponRate" xlink:label="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeCouponRate_0EDDE004062C585BB52D209678DD451E" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_643159BB475F5BD03157209678DD68C6" xlink:to="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeCouponRate_0EDDE004062C585BB52D209678DD451E" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AvailableForSaleSecuritiesWeightedAverageLifeYield" xlink:label="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeYield_35306252C5A75C7D5361209678DD8D26" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_643159BB475F5BD03157209678DD68C6" xlink:to="loc_agnc_AvailableForSaleSecuritiesWeightedAverageLifeYield_35306252C5A75C7D5361209678DD8D26" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfChangesInAccumulatedOciForAvailableForSaleSecurityDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_D8CDE16194297130ED892095FD1C74CD" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_FBF935096082C27B7DE62095FD1CEFF6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_D8CDE16194297130ED892095FD1C74CD" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_FBF935096082C27B7DE62095FD1CEFF6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_334BCBBB542E643437C92095FD1C17AA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_FBF935096082C27B7DE62095FD1CEFF6" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_334BCBBB542E643437C92095FD1C17AA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_210D49AFA5917E1405492095FD1C8F85_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_334BCBBB542E643437C92095FD1C17AA" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_210D49AFA5917E1405492095FD1C8F85_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_210D49AFA5917E1405492095FD1C8F85" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_334BCBBB542E643437C92095FD1C17AA" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_210D49AFA5917E1405492095FD1C8F85" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_919199F9952E597815C92095FD1CB28C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_210D49AFA5917E1405492095FD1C8F85" xlink:to="loc_us-gaap_AgencySecuritiesMember_919199F9952E597815C92095FD1CB28C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AccumulatedOtherComprehensiveIncomeLossRollForward" xlink:label="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_2797DD31C5619254B2902095FD1C307E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D8CDE16194297130ED892095FD1C74CD" xlink:to="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_2797DD31C5619254B2902095FD1C307E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_09B2D7D8FB72806C5B572095FD1C0C0A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_2797DD31C5619254B2902095FD1C307E" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_09B2D7D8FB72806C5B572095FD1C0C0A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_251E8E53F719742ACA422095FD1C8567" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_2797DD31C5619254B2902095FD1C307E" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_251E8E53F719742ACA422095FD1C8567" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization" xlink:label="loc_agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization_8D641C13EADD873042FA2095FD1C8642" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_AccumulatedOtherComprehensiveIncomeLossRollForward_2797DD31C5619254B2902095FD1C307E" xlink:to="loc_agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization_8D641C13EADD873042FA2095FD1C8642" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfContinuousUnrealizedLossPositionsOfAvailableForSaleSecurityDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_37E297D8FBE89D1977512096E3F403B1" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_B0B328668E43F538773D2096E3F4A0A2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_37E297D8FBE89D1977512096E3F403B1" xlink:to="loc_us-gaap_StatementTable_B0B328668E43F538773D2096E3F4A0A2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_47FE31527AECDC2741F82096E3F44515" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_B0B328668E43F538773D2096E3F4A0A2" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_47FE31527AECDC2741F82096E3F44515" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_0D909BF3721A8022B0B32096E3F48A13_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_47FE31527AECDC2741F82096E3F44515" xlink:to="loc_us-gaap_EquityComponentDomain_0D909BF3721A8022B0B32096E3F48A13_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_0D909BF3721A8022B0B32096E3F48A13" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_47FE31527AECDC2741F82096E3F44515" xlink:to="loc_us-gaap_EquityComponentDomain_0D909BF3721A8022B0B32096E3F48A13" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_5E3FDF900F3A4204960B2096E3F46730" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0D909BF3721A8022B0B32096E3F48A13" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_5E3FDF900F3A4204960B2096E3F46730" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_60881470B60ACB9671812096E3F40D98" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_37E297D8FBE89D1977512096E3F403B1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_60881470B60ACB9671812096E3F40D98" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses_D6BA6FEC983D050EC65E2096E3F5F662" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_37E297D8FBE89D1977512096E3F403B1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses_D6BA6FEC983D050EC65E2096E3F5F662" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_EBBD178191A2D9FEC4062096E3F56950" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_37E297D8FBE89D1977512096E3F403B1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_EBBD178191A2D9FEC4062096E3F56950" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses_48EA879B2D49F853F07A2096E3F55AFB" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_37E297D8FBE89D1977512096E3F403B1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses_48EA879B2D49F853F07A2096E3F55AFB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_7993EA2036AC98C755082096E3F50018" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_37E297D8FBE89D1977512096E3F403B1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_7993EA2036AC98C755082096E3F50018" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses_D95EA4FD76070CC9F9742096E3F54B6D" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_37E297D8FBE89D1977512096E3F403B1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses_D95EA4FD76070CC9F9742096E3F54B6D" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfInvestmentInAgencySecurityDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_D7FE83C8C87B9100A0062095B43A4F3C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_D7FE83C8C87B9100A0062095B43A4F3C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_257EEF3370C6FA1A527E2095B43A40C6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_D7FE83C8C87B9100A0062095B43A4F3C" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_257EEF3370C6FA1A527E2095B43A40C6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_6A1882E6BA20BBA10F9D2095B43A7D85_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_257EEF3370C6FA1A527E2095B43A40C6" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_6A1882E6BA20BBA10F9D2095B43A7D85_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_6A1882E6BA20BBA10F9D2095B43A7D85" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_257EEF3370C6FA1A527E2095B43A40C6" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_6A1882E6BA20BBA10F9D2095B43A7D85" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FixedIncomeSecuritiesMember" xlink:label="loc_us-gaap_FixedIncomeSecuritiesMember_77FDA9321470BDDC84EF2095B43A1DC9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_6A1882E6BA20BBA10F9D2095B43A7D85" xlink:to="loc_us-gaap_FixedIncomeSecuritiesMember_77FDA9321470BDDC84EF2095B43A1DC9" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AdjustableRateMember" xlink:label="loc_agnc_AdjustableRateMember_649EE6B168390AE066BA2095B43AFCC6" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_6A1882E6BA20BBA10F9D2095B43A7D85" xlink:to="loc_agnc_AdjustableRateMember_649EE6B168390AE066BA2095B43AFCC6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CollateralizedMortgageObligationsMember" xlink:label="loc_us-gaap_CollateralizedMortgageObligationsMember_7CAD9AEB1631DB75F5582095B43AA6D9" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_6A1882E6BA20BBA10F9D2095B43A7D85" xlink:to="loc_us-gaap_CollateralizedMortgageObligationsMember_7CAD9AEB1631DB75F5582095B43AA6D9" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_InterestOnlyAndPrincipalOnlyStripMember" xlink:label="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_3D639ACEEBAA3626BEF52095B43ABC71" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_6A1882E6BA20BBA10F9D2095B43A7D85" xlink:to="loc_agnc_InterestOnlyAndPrincipalOnlyStripMember_3D639ACEEBAA3626BEF52095B43ABC71" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_34867FE7DF53262F0FFB2095B43A9CD5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_D7FE83C8C87B9100A0062095B43A4F3C" xlink:to="loc_us-gaap_InvestmentTypeAxis_34867FE7DF53262F0FFB2095B43A9CD5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_D97E10C5056599014D712095B43AD82C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_34867FE7DF53262F0FFB2095B43A9CD5" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_D97E10C5056599014D712095B43AD82C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_D97E10C5056599014D712095B43AD82C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_34867FE7DF53262F0FFB2095B43A9CD5" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_D97E10C5056599014D712095B43AD82C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_107648C29C05DF1D8C462095B43AB141" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_D97E10C5056599014D712095B43AD82C" xlink:to="loc_us-gaap_AgencySecuritiesMember_107648C29C05DF1D8C462095B43AB141" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAmortizedCost" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_BCB0135CCC05D9C265542095B43A6BBF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_BCB0135CCC05D9C265542095B43A6BBF" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AgencySecuritiesGrossUnrealizedGain" xlink:label="loc_agnc_AgencySecuritiesGrossUnrealizedGain_22B9DDFD601CB7B019E52095B43AA726" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:to="loc_agnc_AgencySecuritiesGrossUnrealizedGain_22B9DDFD601CB7B019E52095B43AA726" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AgencySecuritiesGrossUnrealizedLoss" xlink:label="loc_agnc_AgencySecuritiesGrossUnrealizedLoss_77A4AE0260DABFECD5072095B43AF5AB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:to="loc_agnc_AgencySecuritiesGrossUnrealizedLoss_77A4AE0260DABFECD5072095B43AF5AB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_C43013D2386EA8D373232095B43A1D54" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:to="loc_us-gaap_AvailableForSaleSecurities_C43013D2386EA8D373232095B43A1D54" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TradingSecuritiesCost" xlink:label="loc_us-gaap_TradingSecuritiesCost_08E2251BA4CA75151B222095B43A9AEF" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:to="loc_us-gaap_TradingSecuritiesCost_08E2251BA4CA75151B222095B43A9AEF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TradingSecuritiesOther" xlink:label="loc_us-gaap_TradingSecuritiesOther_28EC5A564AD47E46A7402095B43AC8DD" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:to="loc_us-gaap_TradingSecuritiesOther_28EC5A564AD47E46A7402095B43AC8DD" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AgencySecuritiesAmortizedCost" xlink:label="loc_agnc_AgencySecuritiesAmortizedCost_BC45B8F31065CF3803A42095B43A04A7" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:to="loc_agnc_AgencySecuritiesAmortizedCost_BC45B8F31065CF3803A42095B43A04A7" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TotalAgencySecurities" xlink:label="loc_agnc_TotalAgencySecurities_35872D8F642E7BB3EE022095B43AF9E2" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_C3E62A5E5CE2CF5438072095B43AFB5E" xlink:to="loc_agnc_TotalAgencySecurities_35872D8F642E7BB3EE022095B43AF9E2" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesSummaryOfNetGainFromSaleOfAgencySecuritiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_111CFF419A897708352629B76AF30EB8" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_126A97D46462511642D229B76AF3C593" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_111CFF419A897708352629B76AF30EB8" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_126A97D46462511642D229B76AF3C593" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_UnderlyingAssetClassAxis" xlink:label="loc_us-gaap_UnderlyingAssetClassAxis_10B4BFEC0378090D92B529B76AF30AD4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_126A97D46462511642D229B76AF3C593" xlink:to="loc_us-gaap_UnderlyingAssetClassAxis_10B4BFEC0378090D92B529B76AF30AD4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_UnderlyingAssetClassDomain" xlink:label="loc_us-gaap_UnderlyingAssetClassDomain_063C58BFE9459D278CD729B76AF38E68_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_UnderlyingAssetClassAxis_10B4BFEC0378090D92B529B76AF30AD4" xlink:to="loc_us-gaap_UnderlyingAssetClassDomain_063C58BFE9459D278CD729B76AF38E68_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_UnderlyingAssetClassDomain" xlink:label="loc_us-gaap_UnderlyingAssetClassDomain_063C58BFE9459D278CD729B76AF38E68" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_UnderlyingAssetClassAxis_10B4BFEC0378090D92B529B76AF30AD4" xlink:to="loc_us-gaap_UnderlyingAssetClassDomain_063C58BFE9459D278CD729B76AF38E68" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_2F304AE0A69976760B6429B76AF323B7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_063C58BFE9459D278CD729B76AF38E68" xlink:to="loc_us-gaap_AgencySecuritiesMember_2F304AE0A69976760B6429B76AF323B7" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_CostOfSaleOfAvailableForSaleSecuities" xlink:label="loc_agnc_CostOfSaleOfAvailableForSaleSecuities_7C7FFD823C0A8CD4D06329B76AF36A5B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_111CFF419A897708352629B76AF30EB8" xlink:to="loc_agnc_CostOfSaleOfAvailableForSaleSecuities_7C7FFD823C0A8CD4D06329B76AF36A5B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities_B805A0BF8597677E156B29B76AF33C8F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_111CFF419A897708352629B76AF30EB8" xlink:to="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities_B805A0BF8597677E156B29B76AF33C8F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GainLossOnSalesOfMortgageBackedSecuritiesMBS" xlink:label="loc_us-gaap_GainLossOnSalesOfMortgageBackedSecuritiesMBS_CCDF475A6F62E5BA3E6929B76AF3DD0C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_111CFF419A897708352629B76AF30EB8" xlink:to="loc_us-gaap_GainLossOnSalesOfMortgageBackedSecuritiesMBS_CCDF475A6F62E5BA3E6929B76AF3DD0C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MarketableSecuritiesRealizedGainLoss" xlink:label="loc_us-gaap_MarketableSecuritiesRealizedGainLoss_8EE2465EF9D8E5FA6C5729B76AF3FDCC" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_111CFF419A897708352629B76AF30EB8" xlink:to="loc_us-gaap_MarketableSecuritiesRealizedGainLoss_8EE2465EF9D8E5FA6C5729B76AF3FDCC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses_371052CE7219FAE33B6729B76AF3A963" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_111CFF419A897708352629B76AF30EB8" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses_371052CE7219FAE33B6729B76AF3A963" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/InvestmentSecuritiesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/Organization" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/OrganizationDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssets" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsAssetsPledgedAsCollateralDetails" xlink:type="extended">
    <loc xlink:href="agnc-20150331.xsd#agnc_OffsettingAssetsAndLiabilitiesLineItems" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_057403996ED1FD43B37E20B74E064718" xlink:type="locator" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OffsettingAssetsAndLiabilitiesTable" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesTable_55BBFD3A4882CFA826CF20B74E05806A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_057403996ED1FD43B37E20B74E064718" xlink:to="loc_agnc_OffsettingAssetsAndLiabilitiesTable_55BBFD3A4882CFA826CF20B74E05806A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_D2624F1B1E10853FB78D20B74E0599C4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_55BBFD3A4882CFA826CF20B74E05806A" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_D2624F1B1E10853FB78D20B74E0599C4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_558E9DCF35DE4CAD5C1420B74E0545D0_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_D2624F1B1E10853FB78D20B74E0599C4" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_558E9DCF35DE4CAD5C1420B74E0545D0_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_558E9DCF35DE4CAD5C1420B74E0545D0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_D2624F1B1E10853FB78D20B74E0599C4" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_558E9DCF35DE4CAD5C1420B74E0545D0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_5008EAF9326E5F9DA55620B74E057DA0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_558E9DCF35DE4CAD5C1420B74E0545D0" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_5008EAF9326E5F9DA55620B74E057DA0" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_UnderPrimeBrokerAgreementsMember" xlink:label="loc_agnc_UnderPrimeBrokerAgreementsMember_DA7A6CC939DF1C719BD020B74E057763" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_558E9DCF35DE4CAD5C1420B74E0545D0" xlink:to="loc_agnc_UnderPrimeBrokerAgreementsMember_DA7A6CC939DF1C719BD020B74E057763" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ExcludingCashReceivedMember" xlink:label="loc_agnc_ExcludingCashReceivedMember_1C86DF8AD41A631A192C20B74E0525CD" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_558E9DCF35DE4CAD5C1420B74E0545D0" xlink:to="loc_agnc_ExcludingCashReceivedMember_1C86DF8AD41A631A192C20B74E0525CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassAxis" xlink:label="loc_invest_InvestmentSecuritiesClassAxis_6425502840D6BD9164FF20B74E0578E9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_55BBFD3A4882CFA826CF20B74E05806A" xlink:to="loc_invest_InvestmentSecuritiesClassAxis_6425502840D6BD9164FF20B74E0578E9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassDomain" xlink:label="loc_invest_InvestmentSecuritiesClassDomain_915A9A9D1BD377B64D5720B74E05B3D0_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_invest_InvestmentSecuritiesClassAxis_6425502840D6BD9164FF20B74E0578E9" xlink:to="loc_invest_InvestmentSecuritiesClassDomain_915A9A9D1BD377B64D5720B74E05B3D0_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassDomain" xlink:label="loc_invest_InvestmentSecuritiesClassDomain_915A9A9D1BD377B64D5720B74E05B3D0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_invest_InvestmentSecuritiesClassAxis_6425502840D6BD9164FF20B74E0578E9" xlink:to="loc_invest_InvestmentSecuritiesClassDomain_915A9A9D1BD377B64D5720B74E05B3D0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_415973E85CB83DC3789520B74E05AD57" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_915A9A9D1BD377B64D5720B74E05B3D0" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_415973E85CB83DC3789520B74E05AD57" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_20315B3B1F8079DFA00220B74E05B8D4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_915A9A9D1BD377B64D5720B74E05B3D0" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_20315B3B1F8079DFA00220B74E05B8D4" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_UnderPrimeBrokerAgreementsMember" xlink:label="loc_agnc_UnderPrimeBrokerAgreementsMember_47198DB77EAB9E44E56F20B74E05DEA4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_915A9A9D1BD377B64D5720B74E05B3D0" xlink:to="loc_agnc_UnderPrimeBrokerAgreementsMember_47198DB77EAB9E44E56F20B74E05DEA4" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_IncludesSoldButNotYetSettledSecuritiesMember" xlink:label="loc_agnc_IncludesSoldButNotYetSettledSecuritiesMember_3462BA0A9092A2C32D9820B74E05609A" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_915A9A9D1BD377B64D5720B74E05B3D0" xlink:to="loc_agnc_IncludesSoldButNotYetSettledSecuritiesMember_3462BA0A9092A2C32D9820B74E05609A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_66EE7C37B95F839451B920B74E059598" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_915A9A9D1BD377B64D5720B74E05B3D0" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_66EE7C37B95F839451B920B74E059598" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_D2C860F0C01B6F475D7920B74E0684B5" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_55BBFD3A4882CFA826CF20B74E05806A" xlink:to="loc_us-gaap_InvestmentTypeAxis_D2C860F0C01B6F475D7920B74E0684B5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_0BE8FBD13CD931E7726E20B74E063B46_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_D2C860F0C01B6F475D7920B74E0684B5" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_0BE8FBD13CD931E7726E20B74E063B46_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_0BE8FBD13CD931E7726E20B74E063B46" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_D2C860F0C01B6F475D7920B74E0684B5" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_0BE8FBD13CD931E7726E20B74E063B46" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_90899D82D90C13BEC57420B74E060E62" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_0BE8FBD13CD931E7726E20B74E063B46" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_90899D82D90C13BEC57420B74E060E62" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaap_DerivativeMember_DD6E73E787195FB1C1E620B74E062F07" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_0BE8FBD13CD931E7726E20B74E063B46" xlink:to="loc_us-gaap_DerivativeMember_DD6E73E787195FB1C1E620B74E062F07" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral_AAC8FF37FB835B27D8B520B74E06CD01" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_057403996ED1FD43B37E20B74E064718" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral_AAC8FF37FB835B27D8B520B74E06CD01" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AvailableForSaleSecuritiesPledgedAsCollateralAccruedInterest" xlink:label="loc_agnc_AvailableForSaleSecuritiesPledgedAsCollateralAccruedInterest_EBAA35138EA6F8FA5D7320B74E06A2C4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_057403996ED1FD43B37E20B74E064718" xlink:to="loc_agnc_AvailableForSaleSecuritiesPledgedAsCollateralAccruedInterest_EBAA35138EA6F8FA5D7320B74E06A2C4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalents" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalents_B088859E8B040156ABFC20B74E075E37" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_057403996ED1FD43B37E20B74E064718" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalents_B088859E8B040156ABFC20B74E075E37" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TotalFairValueOfAgencySecuritiesPledgedAndAccruedInterest" xlink:label="loc_agnc_TotalFairValueOfAgencySecuritiesPledgedAndAccruedInterest_CEAC7E0B9A327E33E6FE20B74E07775D" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_057403996ED1FD43B37E20B74E064718" xlink:to="loc_agnc_TotalFairValueOfAgencySecuritiesPledgedAndAccruedInterest_CEAC7E0B9A327E33E6FE20B74E07775D" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsAssetsPledgedFromCounterpartiesDetails" xlink:type="extended">
    <loc xlink:href="agnc-20150331.xsd#agnc_OffsettingAssetsAndLiabilitiesLineItems" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_31A405722AB40A451B4E20B77A548D12" xlink:type="locator" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OffsettingAssetsAndLiabilitiesTable" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesTable_43850C1D8210967ADCCD20B77A5332CE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_31A405722AB40A451B4E20B77A548D12" xlink:to="loc_agnc_OffsettingAssetsAndLiabilitiesTable_43850C1D8210967ADCCD20B77A5332CE" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_0FB4C729207D830E087320B77A532FB2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_43850C1D8210967ADCCD20B77A5332CE" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_0FB4C729207D830E087320B77A532FB2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_6B09B4800AB640E0C44B20B77A5353E3_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_0FB4C729207D830E087320B77A532FB2" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_6B09B4800AB640E0C44B20B77A5353E3_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_6B09B4800AB640E0C44B20B77A5353E3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_0FB4C729207D830E087320B77A532FB2" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_6B09B4800AB640E0C44B20B77A5353E3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaap_DerivativeMember_98F438F6933E8799CBC420B77A53D3DC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_6B09B4800AB640E0C44B20B77A5353E3" xlink:to="loc_us-gaap_DerivativeMember_98F438F6933E8799CBC420B77A53D3DC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_72CCD32C043598CDF8DB20B77A53AB79" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_43850C1D8210967ADCCD20B77A5332CE" xlink:to="loc_us-gaap_InvestmentTypeAxis_72CCD32C043598CDF8DB20B77A53AB79" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_3DC0A5BDFF601F6FAFB520B77A53892D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_72CCD32C043598CDF8DB20B77A53AB79" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_3DC0A5BDFF601F6FAFB520B77A53892D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_3DC0A5BDFF601F6FAFB520B77A53892D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_72CCD32C043598CDF8DB20B77A53AB79" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_3DC0A5BDFF601F6FAFB520B77A53892D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaap_DerivativeMember_AF9B4F779FCEF2CA32E220B77A54DECF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_3DC0A5BDFF601F6FAFB520B77A53892D" xlink:to="loc_us-gaap_DerivativeMember_AF9B4F779FCEF2CA32E220B77A54DECF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassAxis" xlink:label="loc_invest_InvestmentSecuritiesClassAxis_6A39689592DC233D49DE20B77A5471CD" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_43850C1D8210967ADCCD20B77A5332CE" xlink:to="loc_invest_InvestmentSecuritiesClassAxis_6A39689592DC233D49DE20B77A5471CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassDomain" xlink:label="loc_invest_InvestmentSecuritiesClassDomain_F98A61A1B78824CA56B820B77A5463FE_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_invest_InvestmentSecuritiesClassAxis_6A39689592DC233D49DE20B77A5471CD" xlink:to="loc_invest_InvestmentSecuritiesClassDomain_F98A61A1B78824CA56B820B77A5463FE_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentSecuritiesClassDomain" xlink:label="loc_invest_InvestmentSecuritiesClassDomain_F98A61A1B78824CA56B820B77A5463FE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_invest_InvestmentSecuritiesClassAxis_6A39689592DC233D49DE20B77A5471CD" xlink:to="loc_invest_InvestmentSecuritiesClassDomain_F98A61A1B78824CA56B820B77A5463FE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaap_DerivativeMember_940CFB2CABD10804D31820B77A540281" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_F98A61A1B78824CA56B820B77A5463FE" xlink:to="loc_us-gaap_DerivativeMember_940CFB2CABD10804D31820B77A540281" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_3586755B778DFB754CB920B77A5441A1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_F98A61A1B78824CA56B820B77A5463FE" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_3586755B778DFB754CB920B77A5441A1" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ReverseRepurchaseAgreementsMember" xlink:label="loc_agnc_ReverseRepurchaseAgreementsMember_9B95DEC27FF406FA5DDD20B77A54988E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentSecuritiesClassDomain_F98A61A1B78824CA56B820B77A5463FE" xlink:to="loc_agnc_ReverseRepurchaseAgreementsMember_9B95DEC27FF406FA5DDD20B77A54988E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtSecurityAxis" xlink:label="loc_us-gaap_DebtSecurityAxis_6D74D4A81B0DFDF8140320B77A54C800" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_43850C1D8210967ADCCD20B77A5332CE" xlink:to="loc_us-gaap_DebtSecurityAxis_6D74D4A81B0DFDF8140320B77A54C800" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_C08FC269A477C91146E620B77A547BDC_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtSecurityAxis_6D74D4A81B0DFDF8140320B77A54C800" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_C08FC269A477C91146E620B77A547BDC_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_C08FC269A477C91146E620B77A547BDC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtSecurityAxis_6D74D4A81B0DFDF8140320B77A54C800" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_C08FC269A477C91146E620B77A547BDC" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AssetsPledgedtoUsMember" xlink:label="loc_agnc_AssetsPledgedtoUsMember_33FD40E81D16A472F05120B77A54181E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_C08FC269A477C91146E620B77A547BDC" xlink:to="loc_agnc_AssetsPledgedtoUsMember_33FD40E81D16A472F05120B77A54181E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral_A366C069B63E4AD028A820B77A5467BB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_31A405722AB40A451B4E20B77A548D12" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral_A366C069B63E4AD028A820B77A5467BB" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue" xlink:label="loc_agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue_998F5AEFE8CB11CB5DFF20B77A5471D1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_31A405722AB40A451B4E20B77A548D12" xlink:to="loc_agnc_ObligationToReturnSecuritiesBorrowedUnderReverseRepurchaseAgreementsAtFairValue_998F5AEFE8CB11CB5DFF20B77A5471D1" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_RestrictedCashandSecuritiesPledged" xlink:label="loc_agnc_RestrictedCashandSecuritiesPledged_B3912B9C6627AEB48C5C20B77A541CB4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_31A405722AB40A451B4E20B77A548D12" xlink:to="loc_agnc_RestrictedCashandSecuritiesPledged_B3912B9C6627AEB48C5C20B77A541CB4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalents" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalents_DD1E64A6F16078A694FC20B77A540C23" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_31A405722AB40A451B4E20B77A548D12" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalents_DD1E64A6F16078A694FC20B77A540C23" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsNarrativeDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsOffsettingAssetsAndLiabilitiesDetails" xlink:type="extended">
    <loc xlink:href="agnc-20150331.xsd#agnc_OffsettingAssetsAndLiabilitiesLineItems" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_45B020C0F0C093264F7020B7CF72AF6E" xlink:type="locator" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OffsettingAssetsAndLiabilitiesTable" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesTable_774414A6512F5199FA8420B7CF701675" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_45B020C0F0C093264F7020B7CF72AF6E" xlink:to="loc_agnc_OffsettingAssetsAndLiabilitiesTable_774414A6512F5199FA8420B7CF701675" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_B2597C013C02BE76138520B7CF707C6F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_774414A6512F5199FA8420B7CF701675" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_B2597C013C02BE76138520B7CF707C6F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_18D42BFF0307122E821E20B7CF7094F3_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_B2597C013C02BE76138520B7CF707C6F" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_18D42BFF0307122E821E20B7CF7094F3_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_18D42BFF0307122E821E20B7CF7094F3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_B2597C013C02BE76138520B7CF707C6F" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_18D42BFF0307122E821E20B7CF7094F3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_930F99CB663FC42EB06620B7CF708C73" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_18D42BFF0307122E821E20B7CF7094F3" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_930F99CB663FC42EB06620B7CF708C73" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ReverseRepurchaseAgreementsMember" xlink:label="loc_agnc_ReverseRepurchaseAgreementsMember_9CE54CB4E4B3B93A04DA20B7CF709841" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_18D42BFF0307122E821E20B7CF7094F3" xlink:to="loc_agnc_ReverseRepurchaseAgreementsMember_9CE54CB4E4B3B93A04DA20B7CF709841" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_E56F5A138D49897EC49F20B7CF706519" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_774414A6512F5199FA8420B7CF701675" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_E56F5A138D49897EC49F20B7CF706519" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_52F057995641C6BFE8B820B7CF71FEF8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_E56F5A138D49897EC49F20B7CF706519" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_52F057995641C6BFE8B820B7CF71FEF8_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_52F057995641C6BFE8B820B7CF71FEF8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_E56F5A138D49897EC49F20B7CF706519" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_52F057995641C6BFE8B820B7CF71FEF8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsMember" xlink:label="loc_us-gaap_AssetsMember_C5F7D69E802F9456859120B7CF7184A6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_52F057995641C6BFE8B820B7CF71FEF8" xlink:to="loc_us-gaap_AssetsMember_C5F7D69E802F9456859120B7CF7184A6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LiabilityMember" xlink:label="loc_us-gaap_LiabilityMember_D1591559106D30EBAC7320B7CF719D61" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_52F057995641C6BFE8B820B7CF71FEF8" xlink:to="loc_us-gaap_LiabilityMember_D1591559106D30EBAC7320B7CF719D61" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_16792D8CD92D81603B3420B7CF7159F7" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_774414A6512F5199FA8420B7CF701675" xlink:to="loc_us-gaap_DerivativeByNatureAxis_16792D8CD92D81603B3420B7CF7159F7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_02DDD81234C7786B63A020B7CF7114F2_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_16792D8CD92D81603B3420B7CF7159F7" xlink:to="loc_us-gaap_DerivativeNameDomain_02DDD81234C7786B63A020B7CF7114F2_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_02DDD81234C7786B63A020B7CF7114F2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_16792D8CD92D81603B3420B7CF7159F7" xlink:to="loc_us-gaap_DerivativeNameDomain_02DDD81234C7786B63A020B7CF7114F2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_5BC2D2C3453378545D0520B7CF716E6E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_02DDD81234C7786B63A020B7CF7114F2" xlink:to="loc_us-gaap_InterestRateSwapMember_5BC2D2C3453378545D0520B7CF716E6E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_FAB431467E30C5EF6DDD20B7CF71164E" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_774414A6512F5199FA8420B7CF701675" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_FAB431467E30C5EF6DDD20B7CF71164E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_B5688B206BBF4FE2740120B7CF719D37_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_FAB431467E30C5EF6DDD20B7CF71164E" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_B5688B206BBF4FE2740120B7CF719D37_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_B5688B206BBF4FE2740120B7CF719D37" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_FAB431467E30C5EF6DDD20B7CF71164E" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_B5688B206BBF4FE2740120B7CF719D37" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SwaptionMember" xlink:label="loc_us-gaap_SwaptionMember_EC529D8722B172A4994720B7CF715132" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_B5688B206BBF4FE2740120B7CF719D37" xlink:to="loc_us-gaap_SwaptionMember_EC529D8722B172A4994720B7CF715132" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GrossAmountOfRecognizedAssetsLiabilities" xlink:label="loc_agnc_GrossAmountOfRecognizedAssetsLiabilities_DA4CB8B654451FD0371F20B7CF72AE6B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_45B020C0F0C093264F7020B7CF72AF6E" xlink:to="loc_agnc_GrossAmountOfRecognizedAssetsLiabilities_DA4CB8B654451FD0371F20B7CF72AE6B" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_NetAmountofAssetsLiabilitiesPresentedontheBalanceSheet" xlink:label="loc_agnc_NetAmountofAssetsLiabilitiesPresentedontheBalanceSheet_BEF092EB78F16F26768B20B7CF7286C7" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_45B020C0F0C093264F7020B7CF72AF6E" xlink:to="loc_agnc_NetAmountofAssetsLiabilitiesPresentedontheBalanceSheet_BEF092EB78F16F26768B20B7CF7286C7" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GrossAmountsofFinancialInstrumentsNotOffsetontheBalanceSheet" xlink:label="loc_agnc_GrossAmountsofFinancialInstrumentsNotOffsetontheBalanceSheet_B5B0691BE4A580EBF51620B7CF721A13" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_45B020C0F0C093264F7020B7CF72AF6E" xlink:to="loc_agnc_GrossAmountsofFinancialInstrumentsNotOffsetontheBalanceSheet_B5B0691BE4A580EBF51620B7CF721A13" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_GrossAmountsofCashCollateralNotOffsetontheBalanceSheet" xlink:label="loc_agnc_GrossAmountsofCashCollateralNotOffsetontheBalanceSheet_F5A233D40E597C413A4320B7CF724586" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_45B020C0F0C093264F7020B7CF72AF6E" xlink:to="loc_agnc_GrossAmountsofCashCollateralNotOffsetontheBalanceSheet_F5A233D40E597C413A4320B7CF724586" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_NetAmountAfterDeductingGrossAmountsNotOffsetontheBalanceSheetFromNetAmountofAssetsLiabilitiesPresentedontheBalanceSheet" xlink:label="loc_agnc_NetAmountAfterDeductingGrossAmountsNotOffsetontheBalanceSheetFromNetAmountofAssetsLiabilitiesPresentedontheBalanceSheet_13EACC2E9D7583D84C2020B7CF72769D" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_45B020C0F0C093264F7020B7CF72AF6E" xlink:to="loc_agnc_NetAmountAfterDeductingGrossAmountsNotOffsetontheBalanceSheetFromNetAmountofAssetsLiabilitiesPresentedontheBalanceSheet_13EACC2E9D7583D84C2020B7CF72769D" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsSecuritiesPledgedAsCollateralDetails" xlink:type="extended">
    <loc xlink:href="agnc-20150331.xsd#agnc_OffsettingAssetsAndLiabilitiesLineItems" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_503CBD1014E33B2D1ED2E632BEBA87A5" xlink:type="locator" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OffsettingAssetsAndLiabilitiesTable" xlink:label="loc_agnc_OffsettingAssetsAndLiabilitiesTable_2C6BB39919852DBA8B66E632BEBA30D6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_503CBD1014E33B2D1ED2E632BEBA87A5" xlink:to="loc_agnc_OffsettingAssetsAndLiabilitiesTable_2C6BB39919852DBA8B66E632BEBA30D6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_7B829D9BADA91EA30605E632BEBA7764" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_2C6BB39919852DBA8B66E632BEBA30D6" xlink:to="loc_us-gaap_InvestmentTypeAxis_7B829D9BADA91EA30605E632BEBA7764" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_6ABD223E454C27FDC1E6E632BEBAC260_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_7B829D9BADA91EA30605E632BEBA7764" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_6ABD223E454C27FDC1E6E632BEBAC260_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_6ABD223E454C27FDC1E6E632BEBAC260" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_7B829D9BADA91EA30605E632BEBA7764" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_6ABD223E454C27FDC1E6E632BEBAC260" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_2504107109FBBC886C49E632BEBA949E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_6ABD223E454C27FDC1E6E632BEBAC260" xlink:to="loc_us-gaap_AgencySecuritiesMember_2504107109FBBC886C49E632BEBA949E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_39966FDAB5AE7032D078E632BEBA749E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesTable_2C6BB39919852DBA8B66E632BEBA30D6" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_39966FDAB5AE7032D078E632BEBA749E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_448CD59008CDDDE29CB9E632BEBA6D56_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_39966FDAB5AE7032D078E632BEBA749E" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_448CD59008CDDDE29CB9E632BEBA6D56_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_448CD59008CDDDE29CB9E632BEBA6D56" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_39966FDAB5AE7032D078E632BEBA749E" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_448CD59008CDDDE29CB9E632BEBA6D56" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MaturityUpTo30DaysMember" xlink:label="loc_us-gaap_MaturityUpTo30DaysMember_14DB262043128F35C901E632BEBACCDC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_448CD59008CDDDE29CB9E632BEBA6D56" xlink:to="loc_us-gaap_MaturityUpTo30DaysMember_14DB262043128F35C901E632BEBACCDC" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_Maturity31To59DaysMember" xlink:label="loc_agnc_Maturity31To59DaysMember_629CCA73BA1320A2AD9EE632BEBA6B1F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_448CD59008CDDDE29CB9E632BEBA6D56" xlink:to="loc_agnc_Maturity31To59DaysMember_629CCA73BA1320A2AD9EE632BEBA6B1F" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_Maturity60To90DaysMember" xlink:label="loc_agnc_Maturity60To90DaysMember_CD8B9C9CB3630E622119E632BEBA227F" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_448CD59008CDDDE29CB9E632BEBA6D56" xlink:to="loc_agnc_Maturity60To90DaysMember_CD8B9C9CB3630E622119E632BEBA227F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MaturityOver90DaysMember" xlink:label="loc_us-gaap_MaturityOver90DaysMember_647D818F093D29E43FD7E632BEBA367E" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_448CD59008CDDDE29CB9E632BEBA6D56" xlink:to="loc_us-gaap_MaturityOver90DaysMember_647D818F093D29E43FD7E632BEBA367E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MaturityOvernightMember" xlink:label="loc_us-gaap_MaturityOvernightMember_AF9017492820A8598FA2E632BEBAF54E" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_448CD59008CDDDE29CB9E632BEBA6D56" xlink:to="loc_us-gaap_MaturityOvernightMember_AF9017492820A8598FA2E632BEBAF54E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SecurityOwnedAndPledgedAsCollateralFairValue" xlink:label="loc_us-gaap_SecurityOwnedAndPledgedAsCollateralFairValue_6B921B47B44BE5691A5AE632BEBA2800" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_503CBD1014E33B2D1ED2E632BEBA87A5" xlink:to="loc_us-gaap_SecurityOwnedAndPledgedAsCollateralFairValue_6B921B47B44BE5691A5AE632BEBA2800" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AgencySecuritiesPledgedAsCollateralAmortizedCost" xlink:label="loc_agnc_AgencySecuritiesPledgedAsCollateralAmortizedCost_96BEC98BED335E97179FE632BEBAE899" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_503CBD1014E33B2D1ED2E632BEBA87A5" xlink:to="loc_agnc_AgencySecuritiesPledgedAsCollateralAmortizedCost_96BEC98BED335E97179FE632BEBAE899" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_AgencySecuritiesPledgedAsCollateralAccruedInterest" xlink:label="loc_agnc_AgencySecuritiesPledgedAsCollateralAccruedInterest_8A5E80AA98DBD1843DF9E632BEBAA7EC" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_agnc_OffsettingAssetsAndLiabilitiesLineItems_503CBD1014E33B2D1ED2E632BEBA87A5" xlink:to="loc_agnc_AgencySecuritiesPledgedAsCollateralAccruedInterest_8A5E80AA98DBD1843DF9E632BEBAA7EC" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/PledgedAssetsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebt" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtNarrativeDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtRepurchaseArrangementsAndWeightedAverageInterestRatesClassifiedByOriginalMaturitiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_3ACA0567342DD524556720A29A77E9A3" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable" xlink:label="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_28DE48736ADC470F7B0F20A29A76DA2A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_3ACA0567342DD524556720A29A77E9A3" xlink:to="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_28DE48736ADC470F7B0F20A29A76DA2A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtSecurityAxis" xlink:label="loc_us-gaap_DebtSecurityAxis_0FFD616D9C5F89ADD8AE20A29A76F291" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_28DE48736ADC470F7B0F20A29A76DA2A" xlink:to="loc_us-gaap_DebtSecurityAxis_0FFD616D9C5F89ADD8AE20A29A76F291" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_F1E8750030B2AA42737920A29A76989B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtSecurityAxis_0FFD616D9C5F89ADD8AE20A29A76F291" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_F1E8750030B2AA42737920A29A76989B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtSecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_F1E8750030B2AA42737920A29A76989B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtSecurityAxis_0FFD616D9C5F89ADD8AE20A29A76F291" xlink:to="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_F1E8750030B2AA42737920A29A76989B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_B20275E9B00B904972AA20A29A765233" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtSecuritiesDomain_F1E8750030B2AA42737920A29A76989B" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_B20275E9B00B904972AA20A29A765233" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentAxis" xlink:label="loc_invest_InvestmentAxis_384EA44A8553FE1242A320A29A76918E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_28DE48736ADC470F7B0F20A29A76DA2A" xlink:to="loc_invest_InvestmentAxis_384EA44A8553FE1242A320A29A76918E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentDomain" xlink:label="loc_invest_InvestmentDomain_0AB0AF98CFB1CE3222DA20A29A7634E4_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_invest_InvestmentAxis_384EA44A8553FE1242A320A29A76918E" xlink:to="loc_invest_InvestmentDomain_0AB0AF98CFB1CE3222DA20A29A7634E4_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_InvestmentDomain" xlink:label="loc_invest_InvestmentDomain_0AB0AF98CFB1CE3222DA20A29A7634E4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_invest_InvestmentAxis_384EA44A8553FE1242A320A29A76918E" xlink:to="loc_invest_InvestmentDomain_0AB0AF98CFB1CE3222DA20A29A7634E4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_8D23A361B70CEA6B0AEA20A29A76648A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_invest_InvestmentDomain_0AB0AF98CFB1CE3222DA20A29A7634E4" xlink:to="loc_us-gaap_AgencySecuritiesMember_8D23A361B70CEA6B0AEA20A29A76648A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_D2C84CE4338340158B8320A29A76AAEC" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_28DE48736ADC470F7B0F20A29A76DA2A" xlink:to="loc_us-gaap_DebtInstrumentAxis_D2C84CE4338340158B8320A29A76AAEC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_248FCEDB2EF68684F53620A29A7634E9_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_D2C84CE4338340158B8320A29A76AAEC" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_248FCEDB2EF68684F53620A29A7634E9_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_248FCEDB2EF68684F53620A29A7634E9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_D2C84CE4338340158B8320A29A76AAEC" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_248FCEDB2EF68684F53620A29A7634E9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RepurchaseAgreementsMember" xlink:label="loc_us-gaap_RepurchaseAgreementsMember_03FBFA072EAE8CD08A9220A29A76175B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_248FCEDB2EF68684F53620A29A7634E9" xlink:to="loc_us-gaap_RepurchaseAgreementsMember_03FBFA072EAE8CD08A9220A29A76175B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_68880C893AEA6972920C20A29A764C01" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAssetsSoldUnderAgreementsToRepurchaseTable_28DE48736ADC470F7B0F20A29A76DA2A" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_68880C893AEA6972920C20A29A764C01" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_68880C893AEA6972920C20A29A764C01" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_68880C893AEA6972920C20A29A764C01" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MaturityUpTo30DaysMember" xlink:label="loc_us-gaap_MaturityUpTo30DaysMember_D856FFC33C3784DDD49720A29A76902B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:to="loc_us-gaap_MaturityUpTo30DaysMember_D856FFC33C3784DDD49720A29A76902B" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_ThirtyOneToNinetyMember" xlink:label="loc_agnc_ThirtyOneToNinetyMember_BD64069C06D7B766797820A29A778B83" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:to="loc_agnc_ThirtyOneToNinetyMember_BD64069C06D7B766797820A29A778B83" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A4to6MonthsMember" xlink:label="loc_agnc_A4to6MonthsMember_A870CC3F74C0AA3CAE3D20A29A77180C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:to="loc_agnc_A4to6MonthsMember_A870CC3F74C0AA3CAE3D20A29A77180C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A7to9monthsMember" xlink:label="loc_agnc_A7to9monthsMember_8E3D2058EB0438726D2B20A29A772560" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:to="loc_agnc_A7to9monthsMember_8E3D2058EB0438726D2B20A29A772560" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A10to12MonthsMember" xlink:label="loc_agnc_A10to12MonthsMember_804337B44735AB58A60820A29A777126" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:to="loc_agnc_A10to12MonthsMember_804337B44735AB58A60820A29A777126" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A13to24MonthsMember" xlink:label="loc_agnc_A13to24MonthsMember_346FA9D303480962507220A29A77306C" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:to="loc_agnc_A13to24MonthsMember_346FA9D303480962507220A29A77306C" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A25to36monthsMember" xlink:label="loc_agnc_A25to36monthsMember_2447D293727CF8F7DC4C20A29A77F159" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:to="loc_agnc_A25to36monthsMember_2447D293727CF8F7DC4C20A29A77F159" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A37to48monthsMember" xlink:label="loc_agnc_A37to48monthsMember_B3CB96664D2FD793267A20A29A771CBA" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:to="loc_agnc_A37to48monthsMember_B3CB96664D2FD793267A20A29A771CBA" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_A49to60MonthsMember" xlink:label="loc_agnc_A49to60MonthsMember_DB08BA7EE8A1676F71B320A29A779BF2" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_7FADB1808BA215FC541220A29A767010" xlink:to="loc_agnc_A49to60MonthsMember_DB08BA7EE8A1676F71B320A29A779BF2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchase" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_62AA6F0738DF7D3AFD7520A29A7731CF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3ACA0567342DD524556720A29A77E9A3" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_62AA6F0738DF7D3AFD7520A29A7731CF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShortTermDebtWeightedAverageInterestRate" xlink:label="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_9AEA10BDB53EDCF7941E20A29A7734B2" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3ACA0567342DD524556720A29A77E9A3" xlink:to="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_9AEA10BDB53EDCF7941E20A29A7734B2" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_RepurchaseAgreementsWeightedAverageDaysToMaturity" xlink:label="loc_agnc_RepurchaseAgreementsWeightedAverageDaysToMaturity_DE358A9878FB25FD7D0620A29A773894" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3ACA0567342DD524556720A29A77E9A3" xlink:to="loc_agnc_RepurchaseAgreementsWeightedAverageDaysToMaturity_DE358A9878FB25FD7D0620A29A773894" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/RepurchaseAgreementsAndOtherDebtTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquity" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquityAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED4B03FDA17C06FC08DD20C8833DAB64" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_458473108DBE509439AC20C8833C4DFA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED4B03FDA17C06FC08DD20C8833DAB64" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_458473108DBE509439AC20C8833C4DFA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:label="loc_us-gaap_DerivativeByNatureAxis_DE7F8F98933FD4561A7F20C8833C4D88" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_458473108DBE509439AC20C8833C4DFA" xlink:to="loc_us-gaap_DerivativeByNatureAxis_DE7F8F98933FD4561A7F20C8833C4D88" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_7587CEC4E826273AD3CE20C8833C41D5_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeByNatureAxis_DE7F8F98933FD4561A7F20C8833C4D88" xlink:to="loc_us-gaap_DerivativeNameDomain_7587CEC4E826273AD3CE20C8833C41D5_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:label="loc_us-gaap_DerivativeNameDomain_7587CEC4E826273AD3CE20C8833C41D5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeByNatureAxis_DE7F8F98933FD4561A7F20C8833C4D88" xlink:to="loc_us-gaap_DerivativeNameDomain_7587CEC4E826273AD3CE20C8833C41D5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_FC3B0C71AB56BDA8FBEB20C8833D4156" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeNameDomain_7587CEC4E826273AD3CE20C8833C41D5" xlink:to="loc_us-gaap_InterestRateSwapMember_FC3B0C71AB56BDA8FBEB20C8833D4156" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_D0D002E71148929B4A7F20C8833D4A3F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_458473108DBE509439AC20C8833C4DFA" xlink:to="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_D0D002E71148929B4A7F20C8833D4A3F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_EBFBD57DE05279006D2F20C8833D6575_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_D0D002E71148929B4A7F20C8833D4A3F" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_EBFBD57DE05279006D2F20C8833D6575_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_EBFBD57DE05279006D2F20C8833D6575" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_D0D002E71148929B4A7F20C8833D4A3F" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_EBFBD57DE05279006D2F20C8833D6575" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember" xlink:label="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_431A7101C62F3C8414FF20C8833D963D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_EBFBD57DE05279006D2F20C8833D6575" xlink:to="loc_agnc_DiscontinuationOfElectionToAccountForInterestRateSwapsAsDesignatedCashFlowHedgesMember_431A7101C62F3C8414FF20C8833D963D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_29BFCA582F6065DEF91E20C8833D1F44" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_458473108DBE509439AC20C8833C4DFA" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_29BFCA582F6065DEF91E20C8833D1F44" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_228A050E9D9058B3615020C8833D37A9_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_29BFCA582F6065DEF91E20C8833D1F44" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_228A050E9D9058B3615020C8833D37A9_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_228A050E9D9058B3615020C8833D37A9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_29BFCA582F6065DEF91E20C8833D1F44" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_228A050E9D9058B3615020C8833D37A9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AgencySecuritiesMember" xlink:label="loc_us-gaap_AgencySecuritiesMember_FB8CA31D24E3F06D101620C8833D36B5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_228A050E9D9058B3615020C8833D37A9" xlink:to="loc_us-gaap_AgencySecuritiesMember_FB8CA31D24E3F06D101620C8833D36B5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_DC05CFA7B7AEB6129C2C20C8833D76E1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED4B03FDA17C06FC08DD20C8833DAB64" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_DC05CFA7B7AEB6129C2C20C8833D76E1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge" xlink:label="loc_us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge_2C169299CEC17BE1957020C8833D090E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED4B03FDA17C06FC08DD20C8833DAB64" xlink:to="loc_us-gaap_DeferredGainLossOnDiscontinuationOfInterestRateFairValueHedge_2C169299CEC17BE1957020C8833D090E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_E683ACB1EBF21C1CAE5620C8833D21E4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED4B03FDA17C06FC08DD20C8833DAB64" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_E683ACB1EBF21C1CAE5620C8833D21E4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_A845CF7991078F53392120C8833DA8DE" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED4B03FDA17C06FC08DD20C8833DAB64" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_A845CF7991078F53392120C8833DA8DE" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization" xlink:label="loc_agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization_ED9D09276EB62BF6978120C8833D46B4" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED4B03FDA17C06FC08DD20C8833DAB64" xlink:to="loc_agnc_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecurityReversalOfPriorPeriodUnrealizedGainAndLossesOnRealization_ED9D09276EB62BF6978120C8833D46B4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_E9210B81CEF8CC20C36820C8833D3B71" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED4B03FDA17C06FC08DD20C8833DAB64" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_E9210B81CEF8CC20C36820C8833D3B71" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_TotalReclassOfOtherComprehensiveIncome" xlink:label="loc_agnc_TotalReclassOfOtherComprehensiveIncome_D4D9514439D3937BE80620C8833DB980" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED4B03FDA17C06FC08DD20C8833DAB64" xlink:to="loc_agnc_TotalReclassOfOtherComprehensiveIncome_D4D9514439D3937BE80620C8833DB980" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquityCommonStockRepurchaseProgramDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4FEC09164560B9F4449520C7997F8B24" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E0AB8B9DED6D259DB52120C7997ED171" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4FEC09164560B9F4449520C7997F8B24" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E0AB8B9DED6D259DB52120C7997ED171" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_B1DED720293F116EE5F220C7997E45F7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E0AB8B9DED6D259DB52120C7997ED171" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_B1DED720293F116EE5F220C7997E45F7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_F65142D175A9F1A094E720C7997E3334_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_B1DED720293F116EE5F220C7997E45F7" xlink:to="loc_us-gaap_EquityComponentDomain_F65142D175A9F1A094E720C7997E3334_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_F65142D175A9F1A094E720C7997E3334" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_B1DED720293F116EE5F220C7997E45F7" xlink:to="loc_us-gaap_EquityComponentDomain_F65142D175A9F1A094E720C7997E3334" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_2EA216FA39235C79E9DD20C7997F7BB2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_F65142D175A9F1A094E720C7997E3334" xlink:to="loc_us-gaap_CommonStockMember_2EA216FA39235C79E9DD20C7997F7BB2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_A1E91C2931774E435AA120C7998080C8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4FEC09164560B9F4449520C7997F8B24" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_A1E91C2931774E435AA120C7998080C8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_3831F5556A854E175C6A20C7998092E1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4FEC09164560B9F4449520C7997F8B24" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_3831F5556A854E175C6A20C7998092E1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_3CCE23329BE4035C9F2720C79980D712" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4FEC09164560B9F4449520C7997F8B24" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_3CCE23329BE4035C9F2720C79980D712" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_80EB6C62609629E9C5E420C7998057D6" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4FEC09164560B9F4449520C7997F8B24" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_80EB6C62609629E9C5E420C7998057D6" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquityPreferredStockDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F8E463886D16BA5D022320C77430CBC9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F8E463886D16BA5D022320C77430CBC9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_7DC518E8CBF84A4E3DD820C77430DFEE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F8E463886D16BA5D022320C77430CBC9" xlink:to="loc_us-gaap_StatementClassOfStockAxis_7DC518E8CBF84A4E3DD820C77430DFEE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_5ECBB955FC80C6EF820420C774305AF6_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7DC518E8CBF84A4E3DD820C77430DFEE" xlink:to="loc_us-gaap_ClassOfStockDomain_5ECBB955FC80C6EF820420C774305AF6_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_5ECBB955FC80C6EF820420C774305AF6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7DC518E8CBF84A4E3DD820C77430DFEE" xlink:to="loc_us-gaap_ClassOfStockDomain_5ECBB955FC80C6EF820420C774305AF6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredClassAMember" xlink:label="loc_us-gaap_PreferredClassAMember_1FC8E52D4E1F1100ED8120C77430D1AE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5ECBB955FC80C6EF820420C774305AF6" xlink:to="loc_us-gaap_PreferredClassAMember_1FC8E52D4E1F1100ED8120C77430D1AE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_F9C5A640AD17F33E264820C774306D0C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5ECBB955FC80C6EF820420C774305AF6" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_F9C5A640AD17F33E264820C774306D0C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredClassBMember" xlink:label="loc_us-gaap_PreferredClassBMember_AACD7BAFBAA643608A1C20C774302E63" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5ECBB955FC80C6EF820420C774305AF6" xlink:to="loc_us-gaap_PreferredClassBMember_AACD7BAFBAA643608A1C20C774302E63" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SeriesBPreferredStockMember" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_2AF37B453D2EDC61AEF020C774305CA8" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5ECBB955FC80C6EF820420C774305AF6" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_2AF37B453D2EDC61AEF020C774305CA8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_29A9A2074F81DFCEA38120C77430C9A6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_29A9A2074F81DFCEA38120C77430C9A6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaap_PreferredStockCapitalSharesReservedForFutureIssuance_0AE724E659F39676807E20C774301B3D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_PreferredStockCapitalSharesReservedForFutureIssuance_0AE724E659F39676807E20C774301B3D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockDividendRatePercentage" xlink:label="loc_us-gaap_PreferredStockDividendRatePercentage_160A50999604DC98DEBB20C774301FEB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_PreferredStockDividendRatePercentage_160A50999604DC98DEBB20C774301FEB" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PreferredStockAuthorizedButNotIssued" xlink:label="loc_agnc_PreferredStockAuthorizedButNotIssued_E99B5D51FFD21FE043BD20C7743046B1" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_agnc_PreferredStockAuthorizedButNotIssued_E99B5D51FFD21FE043BD20C7743046B1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SaleOfStockPricePerShare" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_D480E9A8D24D804762B220C774308543" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_D480E9A8D24D804762B220C774308543" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_37E893F2FB1D01AF930E20C774304494" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_37E893F2FB1D01AF930E20C774304494" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockLiquidationPreference" xlink:label="loc_us-gaap_PreferredStockLiquidationPreference_DA016F98903AA81FFBD220C77430222B" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_PreferredStockLiquidationPreference_DA016F98903AA81FFBD220C77430222B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_11849F905ADBDBC155E720C77430544B" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_PreferredStockSharesIssued_11849F905ADBDBC155E720C77430544B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaap_SharePrice_0190817187BF8802F6CE20C77430C783" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_SharePrice_0190817187BF8802F6CE20C77430C783" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaap_PreferredStockValue_5FB6140B7EE45F556FDE20C7743053C7" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_us-gaap_PreferredStockValue_5FB6140B7EE45F556FDE20C7743053C7" xlink:type="arc" />
    <loc xlink:href="agnc-20150331.xsd#agnc_PreferredStockPercentInterestPerShare" xlink:label="loc_agnc_PreferredStockPercentInterestPerShare_1AB2E77398703ABAA12B20D3F2F56771" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E93F289854B28755CB3620C774305361" xlink:to="loc_agnc_PreferredStockPercentInterestPerShare_1AB2E77398703ABAA12B20D3F2F56771" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/StockholdersEquityTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/SubsequentEvent" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/SubsequentEventDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_64E476337C02A135895920BA0FABA922" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_5856070740DC24A5D0C920BA0FAA0E9F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_64E476337C02A135895920BA0FABA922" xlink:to="loc_us-gaap_SubsequentEventTable_5856070740DC24A5D0C920BA0FAA0E9F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_2B45E1C59E7DCB2CA50B20BA0FAABEC6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_5856070740DC24A5D0C920BA0FAA0E9F" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_2B45E1C59E7DCB2CA50B20BA0FAABEC6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_660FAC57AE9677C4531720BA0FAB00AA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_2B45E1C59E7DCB2CA50B20BA0FAABEC6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_660FAC57AE9677C4531720BA0FAB00AA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_660FAC57AE9677C4531720BA0FAB00AA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_2B45E1C59E7DCB2CA50B20BA0FAABEC6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_660FAC57AE9677C4531720BA0FAB00AA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_4C824FB66DB6BD40220520BA0FAB3526" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_660FAC57AE9677C4531720BA0FAB00AA" xlink:to="loc_us-gaap_SubsequentEventMember_4C824FB66DB6BD40220520BA0FAB3526" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_010DAF85820E1F9A451E20BA0FAB1123" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_64E476337C02A135895920BA0FABA922" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_010DAF85820E1F9A451E20BA0FAB1123" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <definitionLink xlink:role="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_7D012DD1BB418E0895AF208EACA7DD2C" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_C1496712121669B84EA2208EACA749DF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_7D012DD1BB418E0895AF208EACA7DD2C" xlink:to="loc_us-gaap_DerivativeTable_C1496712121669B84EA2208EACA749DF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_9CF2FB951C04EDC456522092B7497C8B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_C1496712121669B84EA2208EACA749DF" xlink:to="loc_us-gaap_RangeAxis_9CF2FB951C04EDC456522092B7497C8B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_4E06F5ED7C98113E03FE2092B74B0D98_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_9CF2FB951C04EDC456522092B7497C8B" xlink:to="loc_us-gaap_RangeMember_4E06F5ED7C98113E03FE2092B74B0D98_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_4E06F5ED7C98113E03FE2092B74B0D98" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_9CF2FB951C04EDC456522092B7497C8B" xlink:to="loc_us-gaap_RangeMember_4E06F5ED7C98113E03FE2092B74B0D98" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_D14AEFF71372FF604E712092CB96EE89" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_4E06F5ED7C98113E03FE2092B74B0D98" xlink:to="loc_us-gaap_MaximumMember_D14AEFF71372FF604E712092CB96EE89" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_D6126E62CE1581DCACA620928579261A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_C1496712121669B84EA2208EACA749DF" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_D6126E62CE1581DCACA620928579261A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_CB5DBCDA58846E7BE1922092857CD432_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_D6126E62CE1581DCACA620928579261A" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_CB5DBCDA58846E7BE1922092857CD432_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_CB5DBCDA58846E7BE1922092857CD432" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_D6126E62CE1581DCACA620928579261A" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_CB5DBCDA58846E7BE1922092857CD432" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_1A55C9CE62F8D5C0CBE52092A239FB21" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_CB5DBCDA58846E7BE1922092857CD432" xlink:to="loc_us-gaap_InterestRateSwapMember_1A55C9CE62F8D5C0CBE52092A239FB21" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeTermOfContract" xlink:label="loc_us-gaap_DerivativeTermOfContract_A51AE8A8648097ECD375208E826C291C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7D012DD1BB418E0895AF208EACA7DD2C" xlink:to="loc_us-gaap_DerivativeTermOfContract_A51AE8A8648097ECD375208E826C291C" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.agnc.com/role/SummaryOfSignificantAccountingPoliciesPolicy" xlink:type="extended" />
</linkbase>
