QUANTUM CORP /DE/

S-11 quantum-sx1july2026.htm S-1

As filed with the Securities and Exchange Commission on July 13, 2026

Registration No. 333-

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

(Exact Name of Registrant as Specified in Its Charter)

10770 E. Briarwood Avenue

Centennial, CO 80112

(408) 944-4000

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

William H. White

Chief Financial Officer

10770 E. Briarwood Avenue

Centennial, CO 80112

(408) 944-4000

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copy to:

James J. Masetti

Julie Park

Pillsbury Winthrop Shaw Pittman LLP

2400 Hanover Street

Palo Alto, CA 94304-1113

(650) 233-4500

Approximate date of commencement of proposed sale to the public:

From time to time after this registration statement becomes effective.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933 check the following box: x

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act:

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. o

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

Subject to Completion, Dated July 13, 2026

The information in this prospectus is not complete and may be changed. The selling stockholders may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

PRELIMINARY PROSPECTUS

Up to 13,809,707 Shares of Common Stock

This prospectus relates to the resale from time to time by the selling stockholders identified in this prospectus (the “Selling Stockholders”), of up to 13,809,707 shares of our common stock, $0.01 par value per share, consisting of: (i) 10,615,712 shares of common stock (the “PIPE Shares”) issued and sold to certain accredited investors (the “PIPE Investors”) pursuant to a Securities Purchase Agreement, dated as of June 1, 2026 (the “Purchase Agreement”); (ii) 3,083,975 shares of common stock (the "Share Consideration") issued to Dialectic Technology SPV LLC, a Delaware limited liability company ("Dialectic"), in connection with the voluntary conversion of our 10.00% PIK Senior Secured Convertible Notes due 2028 (the "Convertible Notes"); and (iii) up to 110,020 shares of common stock (the "Warrant Shares"),which is the maximum number of shares issuable based on an assumed exercise price of $5.00 upon exercise of a warrant (the "Conversion Warrant") issued to Dialectic as additional consideration for the conversion of the Convertible Notes.

See the section entitled “The Transaction” for a description of these transactions and the section entitled "Selling Stockholders" for additional information about the Selling Stockholders.

Our registration of the shares of our common stock covered by this prospectus does not mean the Selling Stockholders will offer or sell any of the shares of our common stock. The Selling Stockholders may offer, sell, or distribute all or a portion of their shares of common stock publicly or through private transactions at prevailing market prices or at negotiated prices. We will not receive any proceeds from any sale of shares of common stock by the Selling Stockholders pursuant to this prospectus or any prospectus supplement. We may receive proceeds from the exercise of the Conversion Warrant if exercised for cash; however, we cannot predict whether or when the Conversion Warrant will be exercised or whether it will be exercised on a cash or cashless basis. The resale of our common stock being offered by the Selling Stockholders pursuant to this prospectus, or the perception that these sales could occur, could result in a decline in the public trading price of our common stock. We provide more information about how the Selling Stockholders may sell or otherwise dispose of the shares of our common stock in the section entitled "Plan of Distribution." We will bear all costs, expenses, and fees in connection with the registration of the shares of common stock offered hereby. The Selling Stockholders will bear all commissions and discounts attributable to their sales of the shares of common stock offered hereby.

Our shares of common stock are listed on the Nasdaq Global Market under the symbol “QMCO.” On July 10, 2026, the closing price of our common stock was $10.02 per share.

We are a “smaller reporting company” under the federal securities laws and are subject to reduced disclosure and public reporting requirements. See “Prospectus Summary—Smaller Reporting Company.”

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Investing in our common stock involves a high degree of risk. See the sections entitled “Risk Factors” on page 7 and in the documents incorporated by reference in this prospectus. You should carefully consider these risk factors, as well as the other information contained or incorporated by reference in this prospectus, before you invest.

The date of this prospectus is , 2026.

TABLE OF CONTENTS

Neither we nor the Selling Stockholders have authorized anyone to provide you with any information or to make any representations other than those contained or incorporated by reference in this prospectus. We and the Selling Stockholders do not take responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus is an offer to sell only the securities offered hereby and only under circumstances and in jurisdictions where it is lawful to do so. No dealer, salesperson or other person is authorized to give any information or to represent anything not contained or incorporated by reference in this prospectus. This prospectus is not an offer to sell securities, and it is not soliciting an offer to buy securities, in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus or the documents incorporated by reference herein is accurate only as of the date on the front of this prospectus or the date of such incorporated document only, regardless of the time of delivery of this prospectus or any sale of a security. Our business, financial condition, results of operations and prospects may have changed since those dates.

You should read this prospectus and any applicable prospectus supplement or post-effective amendment to the registration statement of which this prospectus forms a part together with the additional information to which we refer you in the section titled “Where You Can Find More Information; Incorporation by Reference.”

All references in this prospectus to “Quantum,” the “Company,” “we,” “us” and “our” refer to Quantum Corporation and its consolidated subsidiaries, except where the context otherwise requires or as otherwise indicated.

“Quantum” and the Quantum logo are our trademarks. This prospectus and the documents incorporated by reference into this prospectus may also contain trademarks and trade names that are the property of their respective owners. We do not intend our use or display of other companies’ trade names, trademarks, or service marks to imply relationships with, or endorsements or sponsorship of us by, these other companies.

i