<SEC-DOCUMENT>0000921895-16-006279.txt : 20161205
<SEC-HEADER>0000921895-16-006279.hdr.sgml : 20161205
<ACCEPTANCE-DATETIME>20161205190455
ACCESSION NUMBER:		0000921895-16-006279
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20161201
FILED AS OF DATE:		20161205
DATE AS OF CHANGE:		20161205

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			QUANTUM CORP /DE/
		CENTRAL INDEX KEY:			0000709283
		STANDARD INDUSTRIAL CLASSIFICATION:	COMPUTER STORAGE DEVICES [3572]
		IRS NUMBER:				942665054
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		224 AIRPORT PARKWAY
		STREET 2:		SUITE 300
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95110
		BUSINESS PHONE:		408 944 4000

	MAIL ADDRESS:	
		STREET 1:		224 AIRPORT PARKWAY
		STREET 2:		SUITE 300
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95110

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Feld Peter A
		CENTRAL INDEX KEY:			0001410600

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13449
		FILM NUMBER:		162034937

	MAIL ADDRESS:	
		STREET 1:		777 THIRD AVENUE, 18TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MITCHELL MARK R
		CENTRAL INDEX KEY:			0001285596

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13449
		FILM NUMBER:		162034938

	MAIL ADDRESS:	
		STREET 1:		777 THIRD AVENUE, 18TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Smith Jeffrey C
		CENTRAL INDEX KEY:			0001362697

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13449
		FILM NUMBER:		162034939

	MAIL ADDRESS:	
		STREET 1:		777 THIRD AVENUE, 18TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form406297109b_12052016.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
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    <periodOfReport>2016-12-01</periodOfReport>

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    <issuer>
        <issuerCik>0000709283</issuerCik>
        <issuerName>QUANTUM CORP /DE/</issuerName>
        <issuerTradingSymbol>QTM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001362697</rptOwnerCik>
            <rptOwnerName>Smith Jeffrey C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>777 THIRD AVENUE, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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            <otherText></otherText>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001285596</rptOwnerCik>
            <rptOwnerName>MITCHELL MARK R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>777 THIRD AVENUE, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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            <otherText></otherText>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001410600</rptOwnerCik>
            <rptOwnerName>Feld Peter A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>777 THIRD AVENUE, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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            <isOfficer>0</isOfficer>
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            <isOther>0</isOther>
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            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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                <value>Common Stock, $0.01 Par Value</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
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            <transactionDate>
                <value>2016-12-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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                    <value>I</value>
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                <natureOfOwnership>
                    <value>By Starboard Value and Opportunity Master Fund Ltd</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01 Par Value</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
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                <value>2016-12-01</value>
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            <deemedExecutionDate></deemedExecutionDate>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
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                    <value>D</value>
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            </transactionAmounts>
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                <sharesOwnedFollowingTransaction>
                    <value>2291250</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Starboard Value and Opportunity S LLC</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01 Par Value</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
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            <transactionDate>
                <value>2016-12-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>104106</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.92</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1870677</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Starboard Value and Opportunity C LP</value>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01 Par Value</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </securityTitle>
            <transactionDate>
                <value>2016-12-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>199518</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.92</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3585136</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Managed Account of Starboard Value LP</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01 Par Value</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </securityTitle>
            <transactionDate>
                <value>2016-12-05</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1479049</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.9201</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8742884</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Starboard Value and Opportunity Master Fund Ltd</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01 Par Value</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </securityTitle>
            <transactionDate>
                <value>2016-12-05</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>331530</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.9201</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
                    <value>1959720</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Starboard Value and Opportunity S LLC</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01 Par Value</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </securityTitle>
            <transactionDate>
                <value>2016-12-05</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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                <transactionShares>
                    <value>270675</value>
                </transactionShares>
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                    <value>0.9201</value>
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                    <value>D</value>
                </transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
                    <value>1600002</value>
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                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
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                    <value>By Starboard Value and Opportunity C LP</value>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01 Par Value</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </securityTitle>
            <transactionDate>
                <value>2016-12-05</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>518746</value>
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                    <value>0.9201</value>
                </transactionPricePerShare>
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                    <value>D</value>
                </transactionAcquiredDisposedCode>
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                    <value>3066390</value>
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                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
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                    <value>By Managed Account of Starboard Value LP</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This Form 4 is filed jointly by Starboard Value and Opportunity Master Fund Ltd (&quot;Starboard V&amp;O Fund&quot;), Starboard Value and Opportunity S LLC (&quot;Starboard S LLC&quot;), Starboard Value and Opportunity C LP (&quot;Starboard C LP&quot;), Starboard Value LP (&quot;Starboard Value LP&quot;), Starboard Value GP LLC (&quot;Starboard Value GP&quot;), Starboard Principal Co LP (&quot;Principal Co&quot;), Starboard Principal Co GP LLC (&quot;Principal GP&quot;), Starboard Value R LP (&quot;Starboard R LP&quot;), Starboard Value R GP LLC (&quot;Starboard R GP&quot;), Jeffrey C. Smith, Mark R. Mitchell and Peter A. Feld (collectively, the &quot;Reporting Persons&quot;). To enable all of the Reporting Persons to gain access to the Securities and Exchange Commission's electronic filing system (which only accepts a maximum of 10 joint filers per report), this report is the second of two identical reports relating to the same transactions being filed with the Securities and Exchange Commission.</footnote>
        <footnote id="F2">Each Reporting Person may be deemed to be a member of a Section 13(d) group that owns more than 10% of the Issuer's outstanding shares of Common Stock. Each Reporting Person disclaims beneficial ownership of the shares of Common Stock reported herein except to the extent of his or its pecuniary interest therein, and this report shall not be deemed to be an admission that any Reporting Person is the beneficial owner of such shares of Common Stock for purposes of Section 16 or for any other purpose.</footnote>
        <footnote id="F3">Shares of Common Stock beneficially owned by Starboard V&amp;O Fund. Starboard Value LP, as the investment manager of Starboard V&amp;O Fund, may be deemed to be the beneficial owner of the shares of Common Stock beneficially owned by Starboard V&amp;O Fund. Each of Starboard Value GP, as the general partner of Starboard Value LP, Principal Co, as a member of Starboard Value GP, Principal GP, as the general partner of Principal Co, and Messrs. Smith, Mitchell and Feld, as members of Principal GP and as members of each of the Management Committee of Starboard Value GP and the Management Committee of Principal GP, may be deemed to be the beneficial owner of the shares of Common Stock beneficially owned by Starboard V&amp;O Fund.</footnote>
        <footnote id="F4">Shares of Common Stock beneficially owned by Starboard S LLC. Starboard Value LP, as the manager of Starboard S LLC, may be deemed to be the beneficial owner of the shares of Common Stock beneficially owned by Starboard S LLC. Each of Starboard Value GP, as the general partner of Starboard Value LP, Principal Co, as a member of Starboard Value GP, Principal GP, as the general partner of Principal Co, and Messrs. Smith, Mitchell and Feld, as members of Principal GP and as members of each of the Management Committee of Starboard Value GP and the Management Committee of Principal GP, may be deemed to be the beneficial owner of the shares of Common Stock beneficially owned by Starboard S LLC.</footnote>
        <footnote id="F5">Shares of Common Stock beneficially owned by Starboard C LP. Each of Starboard R LP, as the general partner of Starboard C LP, and Starboard R GP, as the general partner of Starboard R LP, may be deemed to be the beneficial owner of the shares of Common Stock beneficially owned by Starboard C LP. Starboard Value LP, as the investment manager of Starboard C LP, may be deemed to be the beneficial owner of the shares of Common Stock beneficially owned by Starboard C LP. Each of Starboard Value GP, as the general partner of Starboard Value LP, Principal Co, as a member of Starboard Value GP, Principal GP, as the general partner of Principal Co, and Messrs. Smith, Mitchell and Feld, as members of Principal GP and as members of each of the Management Committee of Starboard Value GP and the Management Committee of Principal GP, may be deemed to be the beneficial owner of the shares of Common Stock beneficially owned by Starboard C LP.</footnote>
        <footnote id="F6">Shares held in an account managed by Starboard Value LP. Starboard Value GP, as the general partner of Starboard Value LP, Principal Co, as a member of Starboard Value GP, Principal GP, as the general partner of Principal Co, and Messrs. Smith, Mitchell and Feld as members of Principal GP and as members of each of the Management Committee of Starboard Value GP and the Management Committee of Principal GP, may be deemed to be the beneficial owner of the shares of Common Stock beneficially owned by Starboard Value LP.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: /s/ Jeffrey C. Smith</signatureName>
        <signatureDate>2016-12-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Mark R. Mitchell; By: /s/ Jeffrey C. Smith, Attorney in Fact</signatureName>
        <signatureDate>2016-12-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Peter A. Feld; By: /s/ Jeffrey C. Smith, Attorney in Fact</signatureName>
        <signatureDate>2016-12-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</SEC-DOCUMENT>
