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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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 9S/N6hNMuneBDQ6BIGeE4w==

<SEC-DOCUMENT>0001005477-04-003999.txt : 20041112
<SEC-HEADER>0001005477-04-003999.hdr.sgml : 20041111
<ACCEPTANCE-DATETIME>20041112164122
ACCESSION NUMBER:		0001005477-04-003999
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20041109
FILED AS OF DATE:		20041112
DATE AS OF CHANGE:		20041112

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			KOMAG INC /DE/
		CENTRAL INDEX KEY:			0000813347
		STANDARD INDUSTRIAL CLASSIFICATION:	MAGNETIC & OPTICAL RECORDING MEDIA [3695]
		IRS NUMBER:				942914864
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0102

	BUSINESS ADDRESS:	
		STREET 1:		1710 AUTOMATION PWY
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95131
		BUSINESS PHONE:		4085762000

	MAIL ADDRESS:	
		STREET 1:		1710 AUTOMATION PWY
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95131

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			FEINBERG STEPHEN
		CENTRAL INDEX KEY:			0000947822
		STATE OF INCORPORATION:			NY
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-16852
		FILM NUMBER:		041139946

	BUSINESS ADDRESS:	
		STREET 1:		450 PARK AVE
		STREET 2:		28TH FL
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		2128912120

	MAIL ADDRESS:	
		STREET 1:		450 PARK AVE
		STREET 2:		28TH FL
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar123.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-11-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000813347</issuerCik>
        <issuerName>KOMAG INC /DE/</issuerName>
        <issuerTradingSymbol>KOMG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000947822</rptOwnerCik>
            <rptOwnerName>FEINBERG STEPHEN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CERBERUS CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>299 PARK AVENUE - 22ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10171</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2004-11-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>100000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.64</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4296100</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By partnerships, corporations and companies</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2004-11-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>500000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.63</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3796100</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By partnerships, corporations and companies</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Cerberus Partners, L.P., a Delaware limited partnership (&quot;Cerberus&quot;), is the holder of 372,527 shares of the common stock (the &quot;Shares&quot;) of Komag, Incorporated (the &quot;Company&quot;), Cerberus International, Ltd., a corporation organized under the laws of the Bahamas (&quot;International&quot;), is the holder of 1,973,117 Shares, Cerberus Series One Holdings, LLC, a Delaware limited liability company (&quot;Cerberus Series One&quot;), is the holder of 852,261 Shares, Cerberus Series Two Holdings, LLC, a Delaware limited liability company (&quot;Cerberus Series Two&quot;), is the holder of 506,838 Shares, and Cerberus America Series One Holdings, LLC, a Delaware limited liability company (&quot;Cerberus America&quot;), is the holder of 91,357 Shares.  Stephen Feinberg possesses sole power to vote and direct the disposition of all securities of the Company owned by each of Cerberus, International, Cerberus Series One, Cerberus Series Two and Cerberus America.</f
ootnote>
        <footnote id="F2">Thus, for the purposes of Reg. Section 240.13d-3, Stephen Feinberg is deemed to beneficially own 3,796,100 Shares.  Stephen Feinberg's interest in the securities reported herein is limited to the extent of his pecuniary interest in Cerberus, International, Cerberus Series One, Cerberus Series Two and Cerberus America, respectively, if any.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Stephen Feinberg</signatureName>
        <signatureDate>2004-11-10</signatureDate>
    </ownerSignature>
</ownershipDocument>

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