QUANTUM CORP /DE/ — Director's Dealing 2010

Jun 21, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: QUANTUM CORP /DE/ (QTM)
CIK: 0000709283
Period of Report: 2010-06-17

Reporting Person: GACEK JON W (Executive VP, COO, CFO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-06-17	Common Stock	M	15500	$1.46	Acquired	450930	Direct
2010-06-17	Common Stock	S	15500	$2.50	Disposed	435430	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-06-17	Non-Qualified Stock Options	$1.46	M	15500	Disposed	2010-08-22	Common Stock (15500)	Direct

Footnotes

F1: Reflects the exercise of the stock options listed in Table II of this Form 4.

F2: 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.

F3: 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.

F4: The options are fully vested and immediately exercisable.