<SEC-DOCUMENT>0001266824-21-000057.txt : 20210917
<SEC-HEADER>0001266824-21-000057.hdr.sgml : 20210917
<ACCEPTANCE-DATETIME>20210917190216
ACCESSION NUMBER:		0001266824-21-000057
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210826
FILED AS OF DATE:		20210917
DATE AS OF CHANGE:		20210917

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Hunkler Sean
		CENTRAL INDEX KEY:			0001336378

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08703
		FILM NUMBER:		211261703

	MAIL ADDRESS:	
		STREET 1:		C/O WESTERN DIGITAL CORPORATION
		STREET 2:		5601 GREAT OAKS PARKWAY
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95119

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			WESTERN DIGITAL CORP
		CENTRAL INDEX KEY:			0000106040
		STANDARD INDUSTRIAL CLASSIFICATION:	COMPUTER STORAGE DEVICES [3572]
		IRS NUMBER:				330956711
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0703

	BUSINESS ADDRESS:	
		STREET 1:		5601 GREAT OAKS PARKWAY
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95119
		BUSINESS PHONE:		9496727000

	MAIL ADDRESS:	
		STREET 1:		3355 MICHELSON DRIVE SUITE 100
		CITY:			IRVINE
		STATE:			CA
		ZIP:			92612

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GENERAL DIGITAL CORP
		DATE OF NAME CHANGE:	19730125
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-08-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000106040</issuerCik>
        <issuerName>WESTERN DIGITAL CORP</issuerName>
        <issuerTradingSymbol>WDC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001336378</rptOwnerCik>
            <rptOwnerName>Hunkler Sean</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O WESTERN DIGITAL CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>5601 GREAT OAKS PARKWAY</rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95119</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, Global Operations</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-08-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>811</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>156560</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Dividend Equivalent Rights</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-08-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>22.5675</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>22.5675</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1495.0347</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents stock units that have been earned by the Reporting Person as payment in respect of the vesting of performance-based restricted stock units. These shares are scheduled to vest on September 4, 2022.</footnote>
        <footnote id="F2">The amount of securities beneficially owned by the Reporting Person, as disclosed in two Form 4s filed by the Reporting Person on August 31, 2021 and September 7, 2021 (together, the &quot;Subsequent Form 4s&quot;), did not give effect to the transaction reported herein. As a result, the Subsequent Form 4s underreported the number of shares of the Issuer's common stock beneficially owned by the Reporting Person by 811 shares. As of the filing of this report and after giving effect to the transaction reported herein, the Reporting Person beneficially owns 156,560 shares of the Issuer's common stock.</footnote>
        <footnote id="F3">These shares represent the number of incremental dividend equivalents awarded based on the achievement rate of the related performance-based restricted stock units.</footnote>
        <footnote id="F4">The amount of securities beneficially owned by the Reporting Person, as disclosed in the Subsequent Form 4s, did not give effect to the transaction reported herein. As a result, the Subsequent Form 4s underreported the number of dividend equivalents beneficially owned by the Reporting Person by 22.5675. As of the filing of this report and after giving effect to the transaction reported herein, the Reporting Person beneficially owns 1,495.0347 dividend equivalents.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Sandra Garcia Attorney-in-Fact for Sean Hunkler</signatureName>
        <signatureDate>2021-09-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
