<SEC-DOCUMENT>0001021635-17-000096.txt : 20171117
<SEC-HEADER>0001021635-17-000096.hdr.sgml : 20171117
<ACCEPTANCE-DATETIME>20171117175420
ACCESSION NUMBER:		0001021635-17-000096
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20171115
FILED AS OF DATE:		20171117
DATE AS OF CHANGE:		20171117

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:		171212183

	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_151095924612204.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-11-15</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-$.01 par value per share</value>
            </securityTitle>
            <transactionDate>
                <value>2017-11-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10051</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>35.56</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>42048.209</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock-$.01 par value per share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5182.107</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">$35.56. The price reported is a weighted average price.  The shares were sold in multiple transactions with prices ranging from $35.54 to $35.58.  The reporting person undertakes to provide to OGE Energy Corp., any security holder of OGE Energy Corp., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range noted herein.</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 November 16, 2017. The Retirement Savings Plan Statement indicated the number of units in the Common Stock Fund of the Retirement Savings Plan credited to the participant's account at November 16, 2017 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). The number of shares of common stock owned at November 16, 2017, was determined by dividing the dollar value of such units by the closing sale price of the common stock on November 16, 2017.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Patricia D. Horn</signatureName>
        <signatureDate>2017-11-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
