<SEC-DOCUMENT>0000021175-18-000078.txt : 20180524
<SEC-HEADER>0000021175-18-000078.hdr.sgml : 20180524
<ACCEPTANCE-DATETIME>20180524101356
ACCESSION NUMBER:		0000021175-18-000078
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180522
FILED AS OF DATE:		20180524
DATE AS OF CHANGE:		20180524

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Smith Kevin Gene
		CENTRAL INDEX KEY:			0001709370

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-05823
		FILM NUMBER:		18856919

	MAIL ADDRESS:	
		STREET 1:		151 N. FRANKLIN
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CNA FINANCIAL CORP
		CENTRAL INDEX KEY:			0000021175
		STANDARD INDUSTRIAL CLASSIFICATION:	FIRE, MARINE & CASUALTY INSURANCE [6331]
		IRS NUMBER:				366169860
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1025

	BUSINESS ADDRESS:	
		STREET 1:		CNA
		STREET 2:		333 S. WABASH
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60604
		BUSINESS PHONE:		3128225000

	MAIL ADDRESS:	
		STREET 1:		CNA
		STREET 2:		333 S. WABASH
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60604
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_152717122224683.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-05-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000021175</issuerCik>
        <issuerName>CNA FINANCIAL CORP</issuerName>
        <issuerTradingSymbol>CNA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001709370</rptOwnerCik>
            <rptOwnerName>Smith Kevin Gene</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>151 N. FRANKLIN ST.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President &amp; COO, Specialty</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3997</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>49.21</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>27216</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The Company's Incentive Compensation Plan (as amended as of January 1, 2010 and April 27, 2016) permits the withholding of shares of common stock to satisfy tax withholding obligations of the participants upon the lapse of restrictions on those shares. As previously reported, these shares were awarded to Mr. Smith on May 22, 2017.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Stathy Darcy by Power of Attorney for Kevin G. Smith</signatureName>
        <signatureDate>2018-05-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
