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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 LxneYVazzDQ9MEymaT2Bgbn8soWMqLB3+2EEJmPiZj0dcaDiPUDknLDY6N2KXrSO
 HiabTbYA8MiLNPUjfn2J1g==

<SEC-DOCUMENT>0001179110-09-014310.txt : 20091006
<SEC-HEADER>0001179110-09-014310.hdr.sgml : 20091006
<ACCEPTANCE-DATETIME>20091006175056
ACCESSION NUMBER:		0001179110-09-014310
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20091004
FILED AS OF DATE:		20091006
DATE AS OF CHANGE:		20091006

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			GASSER ROBERT C
		CENTRAL INDEX KEY:			0001023087

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32722
		FILM NUMBER:		091108887

	MAIL ADDRESS:	
		STREET 1:		C/O NYFIX INC
		STREET 2:		333 LUDLOW ST
		CITY:			STAMFORD
		STATE:			CT
		ZIP:			06902

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			INVESTMENT TECHNOLOGY GROUP INC
		CENTRAL INDEX KEY:			0000920424
		STANDARD INDUSTRIAL CLASSIFICATION:	SECURITY BROKERS, DEALERS & FLOTATION COMPANIES [6211]
		IRS NUMBER:				133757717
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		380 MADISON AVE
		STREET 2:		4TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017
		BUSINESS PHONE:		2125884000

	MAIL ADDRESS:	
		STREET 1:		380 MADISON AVE
		STREET 2:		4TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-10-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000920424</issuerCik>
        <issuerName>INVESTMENT TECHNOLOGY GROUP INC</issuerName>
        <issuerTradingSymbol>ITG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001023087</rptOwnerCik>
            <rptOwnerName>GASSER ROBERT C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>380 MADISON AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO and President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-10-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4946</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>26.98</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>74891</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>400</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Shares withheld to satisfy the Reporting Person's tax withholding obligations. Please refer to the Amended and Restated Restricted Share Agreement between the Reporting Person and Investment Technology Group, Inc. dated August 6, 2008, filed with Form 10-Q on August 7, 2008. As a result of the achievement of the performance metric for this award, the number of shares as to which beneficial ownership was acquired was 31,250, of which 10,417 shares vested on 10/31/2007, 10,417 shares vested on 10/4/2008, and the remaining 10,416 shares vested on 10/4/2009.</footnote>
        <footnote id="F2">The shares of common stock are held in UTMA custodial accounts on behalf of the Reporting Person's children.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>P. Mats Goebels, by Power of Attorney filed with Form 4 dated April 18, 2007</signatureName>
        <signatureDate>2009-10-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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