<SEC-DOCUMENT>0000909108-15-000047.txt : 20150430
<SEC-HEADER>0000909108-15-000047.hdr.sgml : 20150430
<ACCEPTANCE-DATETIME>20150430170440
ACCESSION NUMBER:		0000909108-15-000047
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20150430
FILED AS OF DATE:		20150430
DATE AS OF CHANGE:		20150430

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			DIAMOND HILL INVESTMENT GROUP INC
		CENTRAL INDEX KEY:			0000909108
		STANDARD INDUSTRIAL CLASSIFICATION:	INVESTMENT ADVICE [6282]
		IRS NUMBER:				650190407
		STATE OF INCORPORATION:			OH
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		325 JOHN H MCCONNELL BLVD
		STREET 2:		SUITE 200
		CITY:			COLUMBUS
		STATE:			OH
		ZIP:			43215
		BUSINESS PHONE:		6142553333

	MAIL ADDRESS:	
		STREET 1:		325 JOHN H MCCONNELL BLVD
		STREET 2:		SUITE 200
		CITY:			COLUMBUS
		STATE:			OH
		ZIP:			43215

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BANC STOCK GROUP INC
		DATE OF NAME CHANGE:	19971016

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HEARTLAND GROUP OF COMPANIES INC
		DATE OF NAME CHANGE:	19940301

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HEARTLAND FINANCIAL GROUP INC
		DATE OF NAME CHANGE:	19930714

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Reeder Paul Arlington III
		CENTRAL INDEX KEY:			0001640859

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24498
		FILM NUMBER:		15820014

	MAIL ADDRESS:	
		STREET 1:		325 JOHN H. MCCONNELL BLVD., SUITE 200
		CITY:			COLUMBUS
		STATE:			OH
		ZIP:			43215
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_143042786860657.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-04-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000909108</issuerCik>
        <issuerName>DIAMOND HILL INVESTMENT GROUP INC</issuerName>
        <issuerTradingSymbol>DHIL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001640859</rptOwnerCik>
            <rptOwnerName>Reeder Paul Arlington III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>325 JOHN H. MCCONNELL BLVD., SUITE 200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>COLUMBUS</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>43215</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</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2015-04-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Restricted stock award representing compensation as director for the ten year period beginning on April 30, 2015 and ending on April 30, 2025.  The award will cliff vest on April 30, 2025.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Gary R Young by POA</signatureName>
        <signatureDate>2015-04-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
