<SEC-DOCUMENT>0000913760-16-000204.txt : 20160104
<SEC-HEADER>0000913760-16-000204.hdr.sgml : 20160104
<ACCEPTANCE-DATETIME>20160104171723
ACCESSION NUMBER:		0000913760-16-000204
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20160104
FILED AS OF DATE:		20160104
DATE AS OF CHANGE:		20160104

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			INTL FCSTONE INC.
		CENTRAL INDEX KEY:			0000913760
		STANDARD INDUSTRIAL CLASSIFICATION:	 [6221]
		IRS NUMBER:				592921318
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		708 THIRD AVENUE
		STREET 2:		SUITE 1500
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017
		BUSINESS PHONE:		212-485-3500

	MAIL ADDRESS:	
		STREET 1:		708 THIRD AVENUE
		STREET 2:		SUITE 1500
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	INTERNATIONAL ASSETS HOLDING CORP
		DATE OF NAME CHANGE:	19931020

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Harrod Patricia Marie
		CENTRAL INDEX KEY:			0001662208

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-36045
		FILM NUMBER:		161319154

	MAIL ADDRESS:	
		STREET 1:		1251 NW BRIARCLIFF PARKWAY
		STREET 2:		SUITE 800
		CITY:			KANSAS CITY
		STATE:			MO
		ZIP:			64116
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>wf-form3_145194583320626.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2016-01-04</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000913760</issuerCik>
        <issuerName>INTL FCSTONE INC.</issuerName>
        <issuerTradingSymbol>INTL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001662208</rptOwnerCik>
            <rptOwnerName>Harrod Patricia Marie</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1251 NW BRIARCLIFF PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 800</rptOwnerStreet2>
            <rptOwnerCity>KANSAS CITY</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>64116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Chief Risk Officer</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Restricted Shares of Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3220</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>20.54</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2016-01-08</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2019-01-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>19.24</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2015-01-16</value>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-01-16</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1333.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Commencing on 1/8/2016 the Optionee shall be entitled to exercise 667 shares of the Option.  Commencing on 1/8/2017 the Optionee shall be entitled to exercise 667 shares of the Option.  Commencing on 1/8/2018 the Optionee shall be entitled to exercise 666 shares of the Option.</footnote>
        <footnote id="F2">Commencing on 1/16/2016 the Optionee shall be entitled to exercise 667 shares of the Option.  Commencing on 1/16/2017 the Optionee shall be entitled to exercise 666 shares of the Option.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Patricia M. Harrod</signatureName>
        <signatureDate>2016-01-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
