UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 5)

QUANTUM CORPORATION

(Name of Issuer)

Common stock, $0.01 par value per share

(Title of Class of Securities)

747906501

(CUSIP Number)

Bryant R. Riley

B. Riley Financial, Inc.

11100 Santa Monica Boulevard, Suite 800

Los Angeles, CA 90045

(818) 884-3737

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

April 22, 2022

(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. ☐

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.

Preliminary Statement:

This Amendment No. 5 (the “Amendment”) hereby amends and supplements the Schedule 13D filed with the Securities and Exchange Commission (the “SEC”) on April 6, 2020, as amended by Amendment No. 1 to Schedule 13D, filed with the SEC on April 28, 2020, by Amendment No. 2 to Schedule 13D, filed with the SEC on February 8, 2021, by Amendment No. 3 to Schedule 13D, filed with the SEC on April 28, 2021, and by Amendment No. 4 to Schedule 13D, filed with the SEC on October 29, 2021 (as so amended, the “Schedule 13D”), relating to shares of Common Stock of Quantum Corporation, a Delaware corporation (the “Issuer” or “Company”). Capitalized terms used but not defined herein shall have the respective meanings set forth in the Schedule 13D. Except as otherwise described herein, the information contained in the Schedule 13D remains in effect.

Item 2 of the Schedule 13D is hereby amended and restated in its entirety as follows:

(a)(b)(c)(f) This Schedule 13D is being filed by the following persons (each, a “Reporting Person” and collectively, the “Reporting Persons”):

(d) During the last five years, none of the Reporting Persons has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

(e) During the last five years, none of the Reporting Persons has been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and, as a result of such proceeding, was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

Item 3 is amended to add the following:

The aggregate purchase price of the 2,019,554 shares of Common Stock acquired by BRS upon the exercise of rights received through the Rights Offering was approximately $4,543,997. The source of funds for acquiring the securities described herein that are directly owned by BRS was the working capital of BRS.

Item 5, Sections (a) and (b) of the Schedule 13D, and Schedules A and B are hereby amended and restated as follows:

(a) - (b)

1. As of the date hereof, BRS beneficially owned directly 2,644,554 shares of Common Stock, representing 2.9% of the Issuer’s Common Stock. BRF is the parent company of BRS. As a result, BRF may be deemed to indirectly beneficially own the Shares held by BRS.

2. As of the date hereof, BRFI beneficially owned directly 3,753,578 shares of Common Stock, representing 4.2% of the Issuer’s Common Stock. BRF is the parent company of BRFI. As a result, BRF may be deemed to indirectly beneficially own the Shares held by BRFI.

3. Bryant R. Riley may beneficially own 990,757 shares of Common Stock representing 1.1% of the Issuer’s Common Stock, of which (i) 897,971 shares are held jointly with his wife, Carleen Riley, received upon distribution from a limited partnership, (ii) 12,614 shares are held as sole custodian for the benefit of Abigail Riley, of which 2,415 were shares received upon distribution from a limited partnership (iii) 12,613 shares are held as sole custodian for the benefit of Eloise Riley, of which 2,415 were shares received upon distribution from a limited partnership, (iv) 12,615 shares are held as sole custodian for the benefit of Susan Riley, of which 2,415 were shares received upon distribution from a limited partnership, and (v) 54,944 shares are held as sole trustee of the Robert Antin Children Irrevocable Trust. Bryant R. Riley may also beneficially own the 6,398.132 shares of Common Stock, representing 7.1% of the Issuer’s Common Stock, held directly by BRS or BRFI in the manner specified in paragraph (1) above. Bryant R. Riley disclaims beneficial ownership of the shares held by BRS and BRFI, or the Robert Antin Children Irrevocable Trust in each case except to the extent of his pecuniary interest therein.

Each of the Reporting Persons, as a member of a “group” with the other Reporting Persons for purposes of Rule 13d-5(b)(1) of the Exchange Act, may be deemed to beneficially own the securities of the Issuer owned by the other Reporting Persons (subject to the Beneficial Ownership Limitation, to the extent applicable). The filing of this Schedule 13D shall not be deemed an admission that the Reporting Persons are, for purposes of Section 13(d) of the Exchange Act, the beneficial owners of any securities of the Issuer it does not directly own or control. Each of the Reporting Persons specifically disclaims beneficial ownership of the securities reported herein that it does not directly own or control.

The following documents are filed as exhibits:

SIGNATURES

After reasonable inquiry and to the best of his or its knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: April 28, 2022

SCHEDULE A

Executive Officers and Directors of B. Riley Financial, Inc.

SCHEDULE B

Transactions within the Past 60 Days

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