UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D
(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO
§ 240.13d-2(a)

(Amendment No. 4)1

Quantum Corporation
(Name of Issuer)

Common Stock, $.01 par value per share
(Title of Class of Securities)

747906 20 4
(CUSIP Number)
 
ERIC SINGER
VIEX CAPITAL ADVISORS, LLC
825 Third Avenue, 33rd Floor
New York, New York 10022
 
(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

May 31, 2016
(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ¨.

Note:  Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.  See § 240.13d-7 for other parties to whom copies are to be sent.


_______________
1              The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).
 
 
 
 
CUSIP NO. 747906 20 4
 
1
NAME OF REPORTING PERSON
 
VIEX Opportunities Fund, LP - Series One*
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
  (a) o
  (b) o
3
SEC USE ONLY
 
4
SOURCE OF FUNDS
 
WC
5
CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)
 
¨
6
CITIZENSHIP OR PLACE OF ORGANIZATION
 
DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH
7
SOLE VOTING POWER
 
- 0 -
8
SHARED VOTING POWER
 
7,407,865
9
SOLE DISPOSITIVE POWER
 
- 0 -
10
SHARED DISPOSITIVE POWER
 
7,407,865
11
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
7,407,865
12
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
 
o
13
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
 
2.8%
14
TYPE OF REPORTING PERSON
 
PN
 
* This Series One is part of a series of VIEX Opportunities Fund, LP, a Delaware series limited partnership.
 
 
2
 
CUSIP NO. 747906 20 4
 
1
NAME OF REPORTING PERSON
 
VIEX Opportunities Fund, LP - Series Two*
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
  (a) o
  (b) o
3
SEC USE ONLY
 
4
SOURCE OF FUNDS
 
WC
5
CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)
 
¨
6
CITIZENSHIP OR PLACE OF ORGANIZATION
 
DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH
7
SOLE VOTING POWER
 
- 0 -
8
SHARED VOTING POWER
 
1,413,191
9
SOLE DISPOSITIVE POWER
 
- 0 -
10
SHARED DISPOSITIVE POWER
 
1,413,191
11
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
1,413,191
12
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
 
o
13
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
 
Less than 1%
14
TYPE OF REPORTING PERSON
 
PN
 
 
* This Series Two is part of a series of VIEX Opportunities Fund, LP, a Delaware series limited partnership.
 
 
3
 
CUSIP NO. 747906 20 4
 
1
NAME OF REPORTING PERSON
 
VIEX Special Opportunities Fund III, LP
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
  (a) o
  (b) o
3
SEC USE ONLY
 
4
SOURCE OF FUNDS
 
WC
5
CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)
 
¨
6
CITIZENSHIP OR PLACE OF ORGANIZATION
 
DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH
7
SOLE VOTING POWER
 
- 0 -
8
SHARED VOTING POWER
 
20,710,666
9
SOLE DISPOSITIVE POWER
 
- 0 -
10
SHARED DISPOSITIVE POWER
 
20,710,666
11
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
20,710,666
12
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
 
o
13
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
 
7.8%
14
TYPE OF REPORTING PERSON
 
PN

 
4
 
CUSIP NO. 747906 20 4
 
1
NAME OF REPORTING PERSON
 
VIEX GP, LLC
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
  (a) o
  (b) o
3
SEC USE ONLY
 
4
SOURCE OF FUNDS
 
AF
5
CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)
 
¨
6
CITIZENSHIP OR PLACE OF ORGANIZATION
 
DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH
7
SOLE VOTING POWER
 
- 0 -
8
SHARED VOTING POWER
 
8,821,056
9
SOLE DISPOSITIVE POWER
 
- 0 -
10
SHARED DISPOSITIVE POWER
 
8,821,056
11
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
8,821,056
12
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
 
o
13
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
 
3.3%
14
TYPE OF REPORTING PERSON
 
OO

 
5
 
CUSIP NO. 747906 20 4
 
1
NAME OF REPORTING PERSON
 
VIEX Special Opportunities GP III, LLC
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
  (a) o
  (b) o
3
SEC USE ONLY
 
4
SOURCE OF FUNDS
 
AF
5
CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)
 
¨
6
CITIZENSHIP OR PLACE OF ORGANIZATION
 
DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH
7
SOLE VOTING POWER
 
- 0 -
8
SHARED VOTING POWER
 
20,710,666
9
SOLE DISPOSITIVE POWER
 
- 0 -
10
SHARED DISPOSITIVE POWER
 
20,710,666
11
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
20,710,666
12
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
 
o
13
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
 
7.8%
14
TYPE OF REPORTING PERSON
 
OO

 
6
 
CUSIP NO. 747906 20 4
 
1
NAME OF REPORTING PERSON
 
VIEX Capital Advisors, LLC
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
  (a) o
  (b) o
3
SEC USE ONLY
 
4
SOURCE OF FUNDS
 
AF
5
CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)
 
¨
6
CITIZENSHIP OR PLACE OF ORGANIZATION
 
DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH
7
SOLE VOTING POWER
 
- 0 -
8
SHARED VOTING POWER
 
29,531,722
9
SOLE DISPOSITIVE POWER
 
- 0 -
10
SHARED DISPOSITIVE POWER
 
29,531,722
11
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
29,531,722
12
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
 
o
13
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
 
11.2%
14
TYPE OF REPORTING PERSON
 
IA

 
7
 
CUSIP NO. 747906 20 4
 
1
NAME OF REPORTING PERSON
 
Eric Singer
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
  (a) o
  (b) o
3
SEC USE ONLY
 
4
SOURCE OF FUNDS
 
AF
5
CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)
 
¨
6
CITIZENSHIP OR PLACE OF ORGANIZATION
 
USA
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH
7
SOLE VOTING POWER
 
- 0 -
8
SHARED VOTING POWER
 
29,531,722
9
SOLE DISPOSITIVE POWER
 
- 0 -
10
SHARED DISPOSITIVE POWER
 
29,531,722
11
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
29,531,722
12
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
 
o
13
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
 
11.2%
14
TYPE OF REPORTING PERSON
 
IN

 
8
 
CUSIP NO. 747906 20 4
 
The following constitutes Amendment No. 4 to the Schedule 13D filed by the undersigned (the “Amendment No. 4”). This Amendment No. 4 amends the Schedule 13D as specifically set forth herein.
 
Item 3.
Source and Amount of Funds or Other Consideration.
 
Item 3 is hereby amended and restated to read as follows:
 
The Shares purchased by Series One were purchased with working capital (which may, at any given time, include margin loans made by brokerage firms in the ordinary course of business) in open market purchases, except as otherwise noted, as set forth in Schedule A, which is incorporated by reference herein. The aggregate purchase price of the 7,407,865 Shares beneficially owned by Series One is approximately $5,769,100, excluding brokerage commissions.
 
The Shares purchased by Series Two were purchased with working capital (which may, at any given time, include margin loans made by brokerage firms in the ordinary course of business) in open market purchases, except as otherwise noted, as set forth in Schedule A, which is incorporated by reference herein. The aggregate purchase price of the 1,413,191 Shares beneficially owned by Series Two is approximately $970,290, excluding brokerage commissions.
 
The Shares purchased by VSO III were purchased with working capital (which may, at any given time, include margin loans made by brokerage firms in the ordinary course of business) in open market purchases, except as otherwise noted, as set forth in Schedule A, which is incorporated by reference herein. The aggregate purchase price of the 20,710,666 Shares beneficially owned by VSO III is approximately $12,772,705, excluding brokerage commissions.
 
Item 5.
Interest in Securities of the Issuer.
 
Items 5(a)-(c) are hereby amended and restated to read as follows:
 
The aggregate percentage of Shares reported owned by each Reporting Person is based upon 264,233,646 Shares outstanding, which is the total number of Shares outstanding as of January 29, 2016 as reported in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on February 5, 2016.
 
A.
Series One
 
 
(a)
As of the close of business on June 1, 2016, Series One beneficially owned 7,407,865 Shares.
 
Percentage: Approximately 2.8%
 
 
(b)
1. Sole power to vote or direct vote: 0
 
2. Shared power to vote or direct vote: 7,407,865
 
3. Sole power to dispose or direct the disposition: 0
 
4. Shared power to dispose or direct the disposition: 7,407,865

 
(c)
Series One has not entered into any transactions since the filing of Amendment No. 3.
 
 
9
 
CUSIP NO. 747906 20 4
 
B.
Series Two
 
 
(a)
As of the close of business on June 1, 2016, Series Two beneficially owned 1,413,191 Shares.
 
Percentage: Less than 1%
 
 
(b)
1. Sole power to vote or direct vote: 0
 
2. Shared power to vote or direct vote: 1,413,191
 
3. Sole power to dispose or direct the disposition: 0
 
4. Shared power to dispose or direct the disposition: 1,413,191

 
(c)
Series Two has not entered into any transactions since the filing of Amendment No. 3.
 
C.
VSO III
 
 
(a)
As of the close of business on June 1, 2016, VSO III beneficially owned 20,710,666 Shares.
 
Percentage: Approximately 7.8%
 
 
(b)
1. Sole power to vote or direct vote: 0
 
2. Shared power to vote or direct vote: 20,710,666
 
3. Sole power to dispose or direct the disposition: 0
 
4. Shared power to dispose or direct the disposition: 20,710,666

 
(c)
The transactions in the Shares by VSO III since the filing of Amendment No. 3 are set forth in Schedule A and are incorporated herein by reference.
 
D.
VIEX GP
 
 
(a)
VIEX GP, as the general partner of Series One and Series Two, may be deemed the beneficial owner of the (i) 7,407,865 shares owned by Series One and (ii) 1,413,191 shares owned by Series Two.
 
Percentage: Approximately 3.3%
 
 
(b)
1. Sole power to vote or direct vote: 0
 
2. Shared power to vote or direct vote: 8,821,056
 
3. Sole power to dispose or direct the disposition: 0
 
4. Shared power to dispose or direct the disposition: 8,821,056

 
 
(c)
VIEX GP has not entered into any transactions in the Shares since the filing of Amendment No. 3.
 
 
10
 
CUSIP NO. 747906 20 4
 
E.
VSO GP III
 
 
(a)
VSO GP III, as the general partner of VSO III, may be deemed the beneficial owner of the 20,710,666 shares owned by VSO III.
 
Percentage: Approximately 7.8%
 
 
(b)
1. Sole power to vote or direct vote: 0
 
2. Shared power to vote or direct vote: 20,710,666
 
3. Sole power to dispose or direct the disposition: 0
 
4. Shared power to dispose or direct the disposition: 20,710,666

 
(c)
VSO GP III has not entered into any transactions in the Shares since the filing of Amendment No. 3.  The transactions in the Shares on behalf of VSO III since the filing of Amendment No. 3 are set forth in Schedule A and are incorporated herein by reference.
 
F.
VIEX Capital
 
 
(a)
VIEX Capital, as the investment manager of Series One and Series Two, may be deemed the beneficial owner of the (i) 7,407,865 Shares owned by Series One, (ii) 1,413,191 Shares owned by Series Two and (iii) 20,710,666 owned by VSO III.
 
Percentage: Approximately 11.2%
 
 
(b)
1. Sole power to vote or direct vote: 0
 
2. Shared power to vote or direct vote: 29,531,722
 
3. Sole power to dispose or direct the disposition: 0
 
4. Shared power to dispose or direct the disposition: 29,531,722

 
(c)
VIEX Capital has not entered into any transactions in the Shares since the filing of Amendment No. 3.  The transactions in the Shares on behalf of VSO III since the filing of Amendment No. 3 are set forth in Schedule A and are incorporated herein by reference.
 
G.
Eric Singer
 
 
(a)
Mr. Singer, as the managing member of VIEX GP and VIEX Capital, may be deemed the beneficial owner of the (i) 7,407,865 Shares owned by Series One, (ii) 1,413,191 Shares owned by Series Two and (iii) 20,710,666 owned by VSO III.
 
Percentage: Approximately 11.2%
 
 
(b)
1. Sole power to vote or direct vote: 0
 
2. Shared power to vote or direct vote: 29,531,722
 
3. Sole power to dispose or direct the disposition: 0
 
4. Shared power to dispose or direct the disposition: 29,531,722

 
(c)
Mr. Singer has not entered into any transactions in the Shares since the filing of Amendment No. 3.  The transactions in the Shares on behalf of VSO III since the filing of Amendment No. 3 are set forth in Schedule A and are incorporated herein by reference.
 
 
The filing of this Schedule 13D shall not be construed as an admission that the Reporting Persons are, for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, the beneficial owners of any of the Shares reported herein.  Each Reporting Person disclaims beneficial ownership of such Shares except to the extent of his or its pecuniary interest therein.
 
 
11
 
CUSIP NO. 747906 20 4
 
SIGNATURES
 
After reasonable inquiry and to the best of his knowledge and belief, the undersigned certifies that the information set forth in this statement is true, complete and correct.
 
Dated:  June 2, 2016

 
VIEX Opportunities Fund, LP – Series One
   
 
By:
VIEX GP, LLC
General Partner
   
 
By:
/s/ Eric Singer
   
Name:
Eric Singer
   
Title:
Managing Member


 
VIEX Opportunities Fund, LP – Series Two
   
 
By:
VIEX GP, LLC
General Partner
   
 
By:
/s/ Eric Singer
   
Name:
Eric Singer
   
Title:
Managing Member


 
VIEX GP, LLC
   
 
By:
/s/ Eric Singer
   
Name:
Eric Singer
   
Title:
Managing Member


 
VIEX Special Opportunities Fund III, LP
   
 
By:
VIEX Special Opportunities GP III, LLC
General Partner
   
 
By:
/s/ Eric Singer
   
Name:
Eric Singer
   
Title:
Managing Member


 
VIEX Special Opportunities GP III, LLC
   
 
By:
/s/ Eric Singer
   
Name:
Eric Singer
   
Title:
Managing Member


 
VIEX Capital Advisors, LLC
   
 
By:
/s/ Eric Singer
   
Name:
Eric Singer
   
Title:
Managing Member

 
/s/ Eric Singer
 
Eric Singer
 
 
12
 
CUSIP NO. 747906 20 4
 
SCHEDULE A
 
Transactions in the Shares Since the Filing of Amendment No. 3
 

Nature of the Transaction
Securities
Purchased/(Sold)
Price Per
Share($)
Date of
Purchase / Sale


VIEX SPECIAL OPPORTUNITIES FUND III, LP


Purchase of Common Stock
3,289,726
0.3675
03/31/2016