FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
GACEK JON W
   2. Issuer Name and Ticker or Trading Symbol
QUANTUM CORP /DE/ [QTM] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
Executive VP, COO, CFO
(Last)
(First)
(Middle)
C/O QUANTUM CORPORATION, 1650 TECHNOLOGY DRIVE, STE. 800		 3. Date of Earliest Transaction (Month/Day/Year)
06/17/2010
(Street)

SAN JOSE, CA 95110		 4. If Amendment, Date Original Filed(Month/Day/Year)
 6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)		 4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)		 6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)		 7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 06/17/2010   M(1)   15,500 A $ 1.46 450,930 D  
Common Stock 06/17/2010   S(2)   15,500 D $ 2.5 435,430 D  

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)		 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)		 5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)		 6. Date Exercisable and Expiration Date
(Month/Day/Year)		 7. Title and Amount of Underlying Securities
(Instr. 3 and 4)		 8. Price of Derivative Security
(Instr. 5)		 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)		 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)		 11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Non-Qualified Stock Options (3) $ 1.46 06/17/2010   M     15,500 08/22/2006(4) 08/22/2010 Common Stock 15,500 $ 0 78,524 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
GACEK JON W
C/O QUANTUM CORPORATION
1650 TECHNOLOGY DRIVE, STE. 800
SAN JOSE, CA 95110		       Executive VP, COO, CFO  

Signatures

 /s/ Astrid Becker-Celik, by Astrid Becker-Celik, Attorney in Fact for Jon W. Gacek   06/21/2010
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Reflects the exercise of the stock options listed in Table II of this Form 4.
(2) The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on February 17, 2010.
(3) These options were granted under the 1999 Stock Incentive Plan of Advanced Digital Information Corporation ("ADIC") and assumed by Quantum Corporation ("Quantum") on August 22, 2006, pursuant to the Agreement and Plan of Merger between ADIC and Quantum. The options were exchanged for options to purchase Quantum stock, at the exchange ratio of 5.9756 per share.
(4) The options are fully vested and immediately exercisable.

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