<SUBMISSION>
<ACCESSION-NUMBER>0001179110-08-015260
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20080813
<FILING-DATE>20080814
<DATE-OF-FILING-DATE-CHANGE>20080814
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>AES CORP
<CIK>0000874761
<ASSIGNED-SIC>4991
<IRS-NUMBER>541163725
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>4300 WILSON BOULEVARD
<CITY>ARLINGTON
<STATE>VA
<ZIP>22203
<PHONE>7035221315
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>4300 WILSON BOULEVARD
<CITY>ARLINGTON
<STATE>VA
<ZIP>22203
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>AES CORPORATION
<DATE-CHANGED>19930328
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>ODEEN PHILIP A
<CIK>0001134555
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12291
<FILM-NUMBER>081019991
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>C/O CONVERGYS CORP
<STREET2>201 EAST FOURTH STREET
<CITY>CINCINNATI
<STATE>OH
<ZIP>45202
<PHONE>5137237000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>N/A
<CITY>N/A
<STATE>OH
<ZIP>45202
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-08-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000874761</issuerCik>
        <issuerName>AES CORP</issuerName>
        <issuerTradingSymbol>AES</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001134555</rptOwnerCik>
            <rptOwnerName>ODEEN PHILIP A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE AES CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>4300 WILSON BOULEVARD</rptOwnerStreet2>
            <rptOwnerCity>ARLINGTON</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>22203</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-08-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.80</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Joint Ownership</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>Philip A. Odeen</signatureName>
        <signatureDate>2008-08-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
