Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^{F1,F2,F3,F4,F5}	Dec 1, 2017	A	16,681	$0.00	A	16,681	D
Common Stock^F1,F2,F4,F6	holding	—	—		—	925,983	I	By: VIEX Opportunities Fund, LP - Series One
Common Stock^F1,F2,F4,F7	holding	—	—		—	176,648	I	By: VIEX Opportunities Fund, LP - Series Two
Common Stock^F1,F2,F4,F8	holding	—	—		—	2,588,833	I	By: VIEX Special Opportunities Fund III, LP

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1This Form 4 is filed jointly by VIEX Opportunities Fund, LP - Series One ("Series One"), a series of VIEX Opportunities Fund, LP ("VIEX Opportunities"), a series limited partnership, VIEX Opportunities Fund, LP - Series Two ("Series Two"), a series of VIEX Opportunities, VIEX Special Opportunities Fund III, LP ("VSO III"), VIEX GP, LLC ("VIEX GP"), VIEX Special Opportunities GP III, LLC ("VSO GP III"), VIEX Capital Advisors, LLC ("VIEX Capital"), and Eric Singer (collectively, the "Reporting Persons").
F2The Reporting Persons are filing this report because each of the Reporting Persons is a member of a Section 13(d) group, disclosed in a Schedule 13D filed on behalf of the Reporting Persons, as it may be amended, which beneficially owns in the aggregate 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.
F3Restricted stock units will fully vest on the earlier to occur of: i) the date of Quantum Corporation's next Annual Stockholder Meeting; and ii) September 1, 2018.
F4Reflects a 1-for-8 reverse stock split of the Issuer's common stock effected on April 18, 2017.
F5Mr. Singer, as the managing member of VIEX GP and VIEX Capital, may be deemed the beneficial owner of the (i) 925,983 Shares owned by Series One, (ii) 176,648 Shares owned by Series Two and (iii) 2,588,833 owned by VSO III.
F6Shares of Common Stock beneficially owned directly by Series One. VIEX GP, as the general partner of Series One, may be deemed the beneficial owner of the shares of Common Stock beneficially owned by Series One. VIEX Capital, as the investment manager of Series One, may be deemed the beneficial owner of the shares of Common Stock beneficially owned by Series One. Mr. Singer, as the managing member of each of VIEX GP and VIEX Capital, may be deemed the beneficial owner of the shares of Common Stock beneficially owned by Series One.
F7Shares of Common Stock beneficially owned directly by Series Two. VIEX GP, as the general partner of Series Two, may be deemed the beneficial owner of the shares of Common Stock beneficially owned by Series Two. VIEX Capital, as the investment manager of Series Two, may be deemed the beneficial owner of the shares of Common Stock beneficially owned by Series Two. Mr. Singer, as the managing member of each of VIEX GP and VIEX Capital, may be deemed the beneficial owner of the shares of Common Stock beneficially owned by Series Two.
F8Shares of Common Stock beneficially owned directly by VSO III. VSO GP III, as the general partner of VSO III, may be deemed the beneficial owner of the shares of Common Stock beneficially owned by VSO III. VIEX Capital, as the investment manager of VSO III, may be deemed the beneficial owner of the shares of Common Stock beneficially owned by VSO III. Mr. Singer, as the managing member of each of VSO GP III and VIEX Capital, may be deemed the beneficial owner of the shares of Common Stock beneficially owned by VSO III.