<SEC-DOCUMENT>0001015328-17-000203.txt : 20171024
<SEC-HEADER>0001015328-17-000203.hdr.sgml : 20171024
<ACCEPTANCE-DATETIME>20171024162018
ACCESSION NUMBER:		0001015328-17-000203
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20171024
FILED AS OF DATE:		20171024
DATE AS OF CHANGE:		20171024

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SWEENEY GARY D
		CENTRAL INDEX KEY:			0001642691

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35077
		FILM NUMBER:		171151150

	MAIL ADDRESS:	
		STREET 1:		WINTRUST FINANCIAL CORPORATION
		STREET 2:		9700 W HIGGINS RD 8TH FLOOR
		CITY:			ROSEMONT
		STATE:			IL
		ZIP:			60018

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			WINTRUST FINANCIAL CORP
		CENTRAL INDEX KEY:			0001015328
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				363873352
		STATE OF INCORPORATION:			IL
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		9700 WEST HIGGINS ROAD, 8TH FLOOR
		CITY:			ROSEMONT
		STATE:			IL
		ZIP:			60018
		BUSINESS PHONE:		8479399000

	MAIL ADDRESS:	
		STREET 1:		9700 WEST HIGGINS ROAD, 8TH FLOOR
		CITY:			ROSEMONT
		STATE:			IL
		ZIP:			60018
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_150887640572380.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-10-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001015328</issuerCik>
        <issuerName>WINTRUST FINANCIAL CORP</issuerName>
        <issuerTradingSymbol>WTFC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001642691</rptOwnerCik>
            <rptOwnerName>SWEENEY GARY D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>9700 WEST HIGGINS ROAD, 8TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ROSEMONT</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60018</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>2017-10-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>338</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>80.58</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2973</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price reported is the weighted average price. The shares were sold in multiple transactions at prices ranging from $80.42 to $80.69, inclusive. The reporting person undertakes to provide to the SEC, the issuer and any security holder full information regarding the number of shares and the prices at which the shares were sold.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Kathleen M. Boege, Attorney-in-fact</signatureName>
        <signatureDate>2017-10-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
