<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0607</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2026-04-21</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000845877</issuerCik>
        <issuerName>FEDERAL AGRICULTURAL MORTGAGE CORP</issuerName>
        <issuerTradingSymbol>AGM</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002131240</rptOwnerCik>
            <rptOwnerName>Talan Mandy M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O FARMER MAC</rptOwnerStreet1>
            <rptOwnerStreet2>2100 PENNSYLVANIA AVENUE, NW, SUITE 450N</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20037</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Principal Accounting Officer</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class C Non-Voting Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>314.3811</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Includes 294 restricted stock units (&quot;RSUs&quot;) granted on March 5, 2026, under the Amended and Restated 2008 Omnibus Incentive Plan of the Federal Agricultural Mortgage Corporation (&quot;Farmer Mac&quot;).  Each RSU represents the contingent right to receive, upon vesting, one share of Farmer Mac's Class C Non-Voting Common Stock.  The RSUs will vest in three equal installments of 98 RSUs vesting on March 31, 2027, March 31, 2028, and March 31, 2029, respectively, if the Reporting Person remains an employee of Farmer Mac on those dates.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Geraldine I. Hayhurst, as attorney-in-fact for Mandy M. Talan</signatureName>
        <signatureDate>2026-04-27</signatureDate>
    </ownerSignature>
</ownershipDocument>