Page 1 of 13 Pages UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (AMENDMENT NO.1)* QUANTUM CORP ------------------------------------------------------ (NAME OF ISSUER) COM DSSG ----------------------------------------------------- (TITLE OF CLASS OF SECURITIES) 747906204 ----------------------------------------------------- (CUSIP NUMBER) December 31, 2000 ----------------------------------------------------- (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: X Rule 13d-1(b) Rule 13d-1(c) Rule 13d-1(d) * 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 the disclosures provided in a prior cover page. The information required in 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). (CONTINUED ON FOLLOWING PAGE(S)) CUSIP NO. 747906204 13G Page 2 of 13 Pages 1. NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NO. OF ABOVE PERSON AXA Assurances I.A.R.D. Mutuelle 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP * (A) [X] (B) [ ] 3. SEC USE ONLY 4. CITIZENSHIP OR PLACE OF ORGANIZATION France NUMBER OF SHARES 5. SOLE VOTING POWER 9,793,315 BENEFICIALLY OWNED AS OF 6. SHARED VOTING POWER 1,888,148 December 31, 2000 BY EACH 7. SOLE DISPOSITIVE POWER 16,779,282 REPORTING PERSON WITH: 8. SHARED DISPOSITIVE POWER 0 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 16,779,282 (Not to be construed as an admission of beneficial ownership) 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES * [ ] 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 11.3% 12. TYPE OF REPORTING PERSON * IC * SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP NO. 747906204 13G Page 3 of 13 Pages 1. NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NO. OF ABOVE PERSON AXA Assurances Vie Mutuelle 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP * (A) [X] (B) [ ] 3. SEC USE ONLY 4. CITIZENSHIP OR PLACE OF France NUMBER OF SHARES 5. SOLE VOTING POWER 9,793,315 BENEFICIALLY OWNED AS OF 6. SHARED VOTING POWER 1,888,148 December 31, 2000 BY EACH 7. SOLE DISPOSITIVE POWER 16,779,282 REPORTING PERSON WITH: 8. SHARED DISPOSITIVE POWER 0 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 16,779,282 (Not to be construed as an admission of beneficial ownership) 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES * [ ] 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 11.3% 12. TYPE OF REPORTING PERSON * IC * SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP NO. 747906204 13G Page 4 of 13 Pages 1. NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NO. OF ABOVE PERSON AXA Conseil Vie Assurance Mutuelle 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP * (A) [X] (B) [ ] 3. SEC USE ONLY 4. CITIZENSHIP OR PLACE OF ORGANIZATION France NUMBER OF SHARES 5. SOLE VOTING POWER 9,793,315 BENEFICIALLY OWNED AS OF 6. SHARED VOTING POWER 1,888,148 December 31, 2000 BY EACH 7. SOLE DISPOSITIVE POWER 16,779,282 REPORTING PERSON WITH: 8. SHARED DISPOSITIVE POWER 0 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 16,779,282 (Not to be construed as an admission of beneficial ownership) 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES * [ ] 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 11.3% 12. TYPE OF REPORTING PERSON * IC * SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP NO. 747906204 13G Page 5 of 13 Pages 1. NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NO. OF ABOVE PERSON AXA Courtage Assurance Mutuelle 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP * (A) [X] (B) [ ] 3. SEC USE ONLY 4. CITIZENSHIP OR PLACE OF ORGANIZATION France NUMBER OF SHARES 5. SOLE VOTING POWER 9,793,315 BENEFICIALLY OWNED AS OF 6. SHARED VOTING POWER 1,888,148 December 31, 2000 BY EACH 7. SOLE DISPOSITIVE POWER 16,779,282 REPORTING PERSON WITH: 8. SHARED DISPOSITIVE POWER 0 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 16,779,282 (Not to be construed as an admission of beneficial ownership) 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES * [ ] 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 11.3% 12. TYPE OF REPORTING PERSON * IC * SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP NO. 747906204 13G Page 6 of 13 Pages 1. NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NO. OF ABOVE PERSON AXA 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP * (A) [X] (B) [ ] 3. SEC USE ONLY 4. CITIZENSHIP OR PLACE OF ORGANIZATION France NUMBER OF SHARES 5. SOLE VOTING POWER 9,793,315 BENEFICIALLY OWNED AS OF 6. SHARED VOTING POWER 1,888,148 December 31, 2000 BY EACH 7. SOLE DISPOSITIVE POWER 16,779,282 REPORTING PERSON WITH: 8. SHARED DISPOSITIVE POWER 0 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 16,779,282 (Not to be construed as an admission of beneficial ownership) 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES * [ ] 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 11.3% 12. TYPE OF REPORTING PERSON * HC * SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP NO. 747906204 13G Page 7 of 13 Pages 1. NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NO. OF ABOVE PERSON AXA FINANCIAL, INC. 13-3623351 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP * (A) [ ] (B) [ ] 3. SEC USE ONLY 4. CITIZENSHIP OR PLACE OF ORGANIZATION State of Delaware NUMBER OF SHARES 5. SOLE VOTING POWER 9,793,315 BENEFICIALLY OWNED AS OF 6. SHARED VOTING POWER 1,888,148 December 31, 2000 BY EACH 7. SOLE DISPOSITIVE POWER 16,779,282 REPORTING PERSON WITH: 8. SHARED DISPOSITIVE POWER 0 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 16,779,282 (Not to be construed as an admission of beneficial ownership) 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES * [ ] 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 11.3% 12. TYPE OF REPORTING PERSON * HC * SEE INSTRUCTIONS BEFORE FILLING OUT! Page 8 of 13 Pages Item 1(a) Name of Issuer: QUANTUM CORP Item 1(b) Address of Issuer's Principal Executive Offices: 500 McCarthy Blvd Milpitas, CA 95035 Item 2(a) and (b) Name of Person Filing and Address of Principal Business Office: AXA Conseil Vie Assurance Mutuelle, AXA Assurances I.A.R.D Mutuelle, and AXA Assurances Vie Mutuelle 370, rue Saint Honore 75001 Paris, France AXA Courtage Assurance Mutuelle 26, rue Louis le Grand 75002 Paris, France as a group (collectively, the 'Mutuelles AXA'). AXA 25, avenue Matignon 75008 Paris, France AXA Financial, Inc. 1290 Avenue of the Americas New York, New York 10104 (Please contact Patrick Meehan at (212) 314-5644 with any questions.) Page 9 of 13 Pages Item 2(c) Citizenship: Mutuelles AXA and AXA - France AXA Financial, Inc. - Delaware Item 2(d) Title of Class of Securities: COM DSSG Item 2(e) CUSIP Number: 747906204 Item 3. Type of Reporting Person: AXA Financial, Inc. as a parent holding company, in accordance with 240.13d-1 (b)(ii)(G). The Mutuelles AXA, as a group, acting as a parent holding company. AXA as a parent holding company.