<SEC-DOCUMENT>0001021635-18-000087.txt : 20180813
<SEC-HEADER>0001021635-18-000087.hdr.sgml : 20180813
<ACCEPTANCE-DATETIME>20180813175947
ACCESSION NUMBER:		0001021635-18-000087
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180809
FILED AS OF DATE:		20180813
DATE AS OF CHANGE:		20180813

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Horn Patricia D
		CENTRAL INDEX KEY:			0001424580

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12579
		FILM NUMBER:		181013599

	MAIL ADDRESS:	
		STREET 1:		PO BOX 321
		CITY:			OKLAHOMA CITY
		STATE:			OK
		ZIP:			73101

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			OGE ENERGY CORP.
		CENTRAL INDEX KEY:			0001021635
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC SERVICES [4911]
		IRS NUMBER:				731481638
		STATE OF INCORPORATION:			OK
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		321 N HARVEY
		STREET 2:		P.O. BOX 321
		CITY:			OKLAHOMA CITY
		STATE:			OK
		ZIP:			73101-0321
		BUSINESS PHONE:		4055533000

	MAIL ADDRESS:	
		STREET 1:		321 N HARVEY
		STREET 2:		P.O. BOX 321
		CITY:			OKLAHOMA CITY
		STATE:			OK
		ZIP:			73101-0321

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	OGE ENERGY CORP
		DATE OF NAME CHANGE:	19960827
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_153419757150218.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-08-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001021635</issuerCik>
        <issuerName>OGE ENERGY CORP.</issuerName>
        <issuerTradingSymbol>OGE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001424580</rptOwnerCik>
            <rptOwnerName>Horn Patricia D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 321</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>OKLAHOMA CITY</rptOwnerCity>
            <rptOwnerState>OK</rptOwnerState>
            <rptOwnerZipCode>73101</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP-Governance &amp; Corp Sec</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock-$.01 par value per share</value>
            </securityTitle>
            <transactionDate>
                <value>2018-08-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3715</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>37</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>40085.203</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock-$.01 par value per share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5493.094</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Retirement Savings</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Open market sell pursuant to a 10b5-1 trading plan adopted by the Reporting Person on November 15, 2017 in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended.</footnote>
        <footnote id="F2">The total includes shares acquired through the reinvestment of dividends that were exempt from reporting pursuant to Rule 16a-11.</footnote>
        <footnote id="F3">The information herein is based on a Retirement Savings Plan Statement dated August 8, 2018. The Retirement Savings Plan Statement indicated the number of shares in the Common Stock Fund of the Retirement Savings Plan credited to the participant's account at August 8, 2018 and includes shares credited since reporting person's last table 1 filing that was exempt from reporting pursuant to Rule 16A-3(f)(1)(i)(B).</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Patricia D. Horn</signatureName>
        <signatureDate>2018-08-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
