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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 e/4u+1QNiU/DCdiZLFIVdA==

<SEC-DOCUMENT>0001023087-04-000003.txt : 20040909
<SEC-HEADER>0001023087-04-000003.hdr.sgml : 20040909
<ACCEPTANCE-DATETIME>20040909162139
ACCESSION NUMBER:		0001023087-04-000003
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040909
FILED AS OF DATE:		20040909
DATE AS OF CHANGE:		20040909

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NYFIX INC
		CENTRAL INDEX KEY:			0000099047
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMPUTER INTEGRATED SYSTEMS DESIGN [7373]
		IRS NUMBER:				061344888
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		333 LUDLOW STREET
		CITY:			STAMFORD
		STATE:			CT
		ZIP:			06902
		BUSINESS PHONE:		2034258000

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	TRINITECH SYSTEMS INC
		DATE OF NAME CHANGE:	19940404

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	TRANS AIRE ELECTRONICS INC
		DATE OF NAME CHANGE:	19910916

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:	000-21324
		FILM NUMBER:		041023196

	BUSINESS ADDRESS:	
		STREET 1:		C/O NYFIX INC
		STREET 2:		333 LUDLOW ST
		CITY:			STAMFORD
		STATE:			CT
		ZIP:			06902
		BUSINESS PHONE:		2034258000

	MAIL ADDRESS:	
		STREET 1:		C/O NYFIX INC
		STREET 2:		333 LUDLOW ST
		CITY:			STAMFORD
		STATE:			CT
		ZIP:			06902
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-09-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000099047</issuerCik>
        <issuerName>NYFIX INC</issuerName>
        <issuerTradingSymbol>NYFX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001023087</rptOwnerCik>
            <rptOwnerName>GASSER ROBERT C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NYFIX INC</rptOwnerStreet1>
            <rptOwnerStreet2>333 LUDLOW ST</rptOwnerStreet2>
            <rptOwnerCity>STAMFORD</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06902</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO of NYFIX Millennium (a)</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-09-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.9</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>55000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>12.8</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2011-09-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>325000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>325000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>12.02</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2011-10-22</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>12500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>3.92</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2012-08-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>100000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>100000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>7.056</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-02-23</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">150,000 options are currently exercisable, remainder vest 75,000 on 9/21/2004 and 100,000 on 9/21/2006</footnote>
        <footnote id="F2">Currently exercisable</footnote>
        <footnote id="F3">60,000 options are currently exercisable, remainder vest 20,000 on 12/31/2004 and 20,000 on 12/31/2005</footnote>
        <footnote id="F4">Options vest 3,334 on 2/23/2005, 3,333 on 2/23/2006 and 3,333 on 2/23/2007</footnote>
    </footnotes>

    <remarks>(a) Also President of NYFIX Transaction Services and NYFIX Clearing Corporation</remarks>

    <ownerSignature>
        <signatureName>Brian Bellardo, by Power of Attorney</signatureName>
        <signatureDate>2004-09-09</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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