SCHEDULE 13G Amendment No. 4 Quantum Corporation Common Stock Cusip # 747906105 Cusip # 747906105 Item 1: Reporting Person - FMR Corp. Item 4: Commonwealth of Massachusetts Item 5: 249,892 Item 6: None Item 7: 12,686,716 Item 8: None Item 9: 12,686,716 Item 11: 9.23% Item 12: HC Cusip # 747906105 Item 1: Reporting Person - Edward C. Johnson 3d Item 4: United States of America Item 5: None Item 6: None Item 7: 12,686,716 Item 8: None Item 9: 12,686,716 Item 11: 9.23% Item 12: IN Cusip # 747906105 Item 1: Reporting Person - Abigail P. Johnson Item 4: United States of America Item 5: None Item 6: None Item 7: 12,686,716 Item 8: None Item 9: 12,686,716 Item 11: 9.23% Item 12: IN SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b) Item 1(a). Name of Issuer: Quantum Corporation Item 1(b). Name of Issuer's Principal Executive Offices: 500 McCarthy Boulevard Milpitas, CA 95035-7908 Item 2(a). Name of Person Filing: FMR Corp. Item 2(b). Address or Principal Business Office or, if None, Residence: 82 Devonshire Street, Boston, Massachusetts 02109 Item 2(c). Citizenship: Not applicable Item 2(d). Title of Class of Securities: Common Stock Item 2(e). CUSIP Number: 747906105 Item 3. This statement is filed pursuant to Rule 13d-1(b) or 13d-2(b) and the person filing, FMR Corp., is a parent holding company in accordance with Section 240.13d-1(b)(ii)(G). (Note: See Item 7). Item 4. Ownership (a) Amount Beneficially Owned: 12,686,716 (b) Percent of Class: 9.23% (c) Number of shares as to which such person has: (i) sole power to vote or to direct the vote: 249,892 (ii) shared power to vote or to direct the vote: None (iii) sole power to dispose or to direct the disposition of: 12,686,716 (iv) shared power to dispose or to direct the disposition of: None Item 5. Ownership of Five Percent or Less of a Class. Not applicable. Item 6. Ownership of More than Five Percent on Behalf of Another Person. Various persons have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the common stock of Quantum Corporation. No one person's interest in the common stock of Quantum Corporation is more than five percent of the total outstanding common stock. Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company. See attached Exhibit(s) A, B, and C. Item 8. Identification and Classification of Members of the Group. Not applicable, see attached Exhibit A. Item 9. Notice of Dissolution of Group. Not applicable. Item 10. Certification. By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired in the ordinary course of business and were not acquired for the purpose of and do not have the effect of changing or influencing the control of the issuer of such securities and were not acquired in connection with or as a participant in any transaction having such purpose or effect. Signature After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this Schedule 13G in connection with FMR Corp.'s beneficial ownership of the common stock of Quantum Corporation at December 31, 1997 is true, complete and correct. February 14, 1998 Date /s/Eric D. Roiter Signature Eric D. Roiter Duly authorized under Power of Attorney dated December 30, 1997, by and on behalf of FMR Corp. and its direct and indirect subsidiaries SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b) Pursuant to the instructions in Item 7 of Schedule 13G, Fidelity Management & Research Company ("Fidelity"), 82 Devonshire Street, Boston, Massachusetts 02109, a wholly-owned subsidiary of FMR Corp. and an investment adviser registered under Section 203 of the Investment Advisers Act of 1940, is the beneficial owner of 12,257,396 shares or 8.91% of the common stock outstanding of Quantum Corporation ("the Company") as a result of acting as investment adviser to various investment companies registered under Section 8 of the Investment Company Act of 1940, and as a result of acting as sub- adviser to Fidelity American Special Situations Trust ("FASST"). The number of shares of common stock of Quantum Corporation owned by the investment companies at December 31, 1997 included 903,587 shares of common stock resulting from the assumed conversion of $10,084,000 principal amount of 5% Convertible Subordinated Debentures 3/1/03 144 A (89,606 shares of common stock for each $1,000 principal amount of debenture). The number of shares of common stock of Quantum Corporation owned by the investment companies at December 31, 1997 included 396,319 shares of common stock resulting from the assumed conversion of $18,360,000 principal amount of 7% Convertible Subordinated Debentures 8/1/04 (21,586616 shares of common stock for each $1,000 principal amount of debenture). FASST is a unit trust established and authorized by the Department of Trade and Industry under the laws of England. The investment adviser of FASST is Fidelity Investment Services Limited, an English company and a subsidiary of Fidelity International Limited ("FIL"). Edward C. Johnson 3d, FMR Corp., through its control of Fidelity, and the funds each has sole power to dispose of the 12,245,796 shares owned by the Funds. Neither FMR Corp. nor Edward C. Johnson 3d, Chairman of FMR Corp., has the sole power to vote or direct the voting of the shares owned directly by the Fidelity Funds, which power resides with the Funds' Boards of Trustees. Fidelity carries out the voting of the shares under written guidelines established by the Funds' Boards of Trustees. FIL, FMR Corp., through its control of Fidelity, and FASST each has sole power to vote and to dispose of the 11,600 shares held by FASST. Fidelity Management Trust Company, 82 Devonshire Street, Boston, Massachusetts 02109, a wholly-owned subsidiary of FMR Corp. and a bank as defined in Section 3(a)(6) of the Securities Exchange Act of 1934, is the beneficial owner of 413,620 shares or 0.30% of the common stock outstanding of the Company as a result of its serving as investment manager of the institutional account(s). The number of shares of common stock of Quantum Corporation owned by the institutional account(s) at December 31, 1997 included 32,120 shares of common stock resulting from the assumed conversion of $1,488,000 principal amount of the 7% Convertible Subordinated Debentures 8/1/04 described above. Edward C. Johnson 3d and FMR Corp., through its control of Fidelity Management Trust Company, each has sole dispositive power over 413,620 shares and sole power to vote or to direct the voting of 222,592 shares, and no power to vote or to direct the voting of 191,028 shares of common stock owned by the institutional account(s) as reported above. Members of the Edward C. Johnson 3d family and trusts for their benefit are the predominant owners of Class B shares of common stock of FMR Corp., representing approximately 49% of the voting power of FMR Corp. Mr. Johnson 3d owns 12.0% and Abigail Johnson owns 24.5% of the aggregate outstanding voting stock of FMR Corp. Mr. Johnson 3d is Chairman of FMR Corp. and Abigail P. Johnson is a Director of FMR Corp. The Johnson family group and all other Class B shareholders have entered into a shareholders' voting agreement under which all Class B shares will be voted in accordance with the majority vote of Class B shares. Accordingly, through their ownership of voting common stock