Aptorum (NASDAQ: APM) delays DiamiR merger cutoff to June 30, 2026

Rhea-AI Filing Summary

Aptorum Group Limited amended its previously reported merger plans with DiamiR Biosciences Corp. by extending key dates. The termination date for their planned merger, originally set at December 31, 2025, has been moved to June 30, 2026 as the parties continue working to satisfy closing conditions.

The related Management Services Agreement and Intellectual Property License Agreement have also been extended to June 30, 2026, with an amendment to the Management Services Agreement filed as an exhibit. Aptorum has filed a Form S-4 registration statement and plans to mail shareholder meeting notices so its shareholders can vote on approving the proposed transactions.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K/A

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of March 2026

Commission File Number: 001-38764

Aptorum Group Limited

17 Hanover Square

London W1S 1BN, United Kingdom

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F  ☒      Form 40-F  ☐

On June 22, 2025, Aptorum Group Limited, a Cayman Islands exempted company with limited liability (“Aptorum”, “APM,” “Aptorum Group” or the “Company”) filed the original report on Form 6-K (the “Initial Report”) to report that it and DiamiR Biosciences Corp., a Delaware corporation (“DiamiR”), entered into an Agreement and Plan of Merger on July 14, 2025, (the “Merger Agreement”), pursuant to which, among other matters, Aptorum will form a direct, wholly owned subsidiary in the state of Delaware (“Merger Sub”), which will merge with and into DiamR, with DiamiR surviving as a wholly owned subsidiary of Aptorum , and the surviving corporation of the merger with the Merger Sub (the “Merger”). Aptorum following the Merger is referred to herein as the “Combined Company.”

Concurrently with the execution of the Merger Agreement, DiamiR and Aptorum Therapeutics Limited, a wholly owned subsidiary of the Company (“Aptorum Therapeutics”), entered into a management services agreement (the “Management Services Agreement”). In addition, concurrently with the execution of the Merger Agreement, DiamiR, DiamiR LLC, a wholly owned subsidiary of DiamiR, the Company and Aptorum Therapeutics entered into an intellectual property license agreement (“Licensing Agreement”), pursuant to which DiamiR and DiamiR LLC shall license on a non-exclusive basis their respective intellectual properties to Aptorum Therapeutics in exchange for upfront and periodic payments and royalties until the earlier of the closing of the Merger or December 31, 2025.

As set forth in the Initial Report, the Termination Date for the Merger was initially set at December 31, 2025; the Management Services Agreement and Licensing Agreement were also set to expire on December 31, 2025. As the parties continue to work towards satisfying the closing conditions for the Merger, they agreed to extend the Termination Date and other agreements to June 30, 2026. The parties signed an amendment to the Management Services Agreement reflecting the extended term (the “Amendment”).

The foregoing description of the Amendment does not purport to be complete and is qualified in its entirety by reference to the Amendment, which is attached hereto as Exhibit 10.3 and is incorporated herein by reference.

Non-Solicitation

This report is not a notice of shareholders meeting or solicitation of a proxy, consent or authorization with respect to any securities or in respect of the proposed transactions and shall not constitute an offer to sell or a solicitation of an offer to buy the securities of Aptorum or DiamiR, nor shall there be any sale of any such securities in any state or jurisdiction in which such offer, solicitation, or sale would be unlawful prior to registration or qualification under the securities laws of such state or jurisdiction. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended.

Additional Information about the Transactions and Where to Find It

In connection with the Merger and related transactions, Aptorum filed a registration statement on Form S-4 (File No. 333-290742) with the SEC on October 6, 2025 and will mail notices of shareholders meeting and other relevant documents to its shareholders. Investors and security holders of Aptorum are advised to read, when available, the Form S-4, and amendments thereto, the notice to shareholders, and amendments thereto, in connection with Aptorum’s solicitation of proxies for its shareholder’ meeting to be held to approve the transactions described herein because the notice to shareholders will contain important information about the transactions and the parties to the transactions. The notices to shareholders will be mailed to Aptorum’s shareholders as of a record date to be established for voting on the proposed transactions. Shareholders will also be able to obtain copies of the notice, without charge, once available, at the SEC’s website at www.sec.gov or by directing a request to: 17 Hanover Square, London W1S 1BN, United Kingdom, attention: Ian Huen.

This Form 6-K shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction. A copy of Aptorum’s registration statement on Form S-4 can be viewed on the SEC’s website.

Financial Statements and Exhibits.

Exhibits.

The following exhibits are attached.

Exhibit		Description
2.1		Merger Agreement by and between Aptorum and DiamiR, dated July 14, 2025 (1)
10.1		Management Services Agreement by and between Aptorum Therapeutics and DiamiR, dated July 14, 2025 (1)
10.2		Intellectual Property License Agreement by and between Aptorum Therapeutics, DiamiR LLC, and DiamiR, dated July 14, 2025(1)
10.3		Amendment to the Management Services Agreement dated as of March 25, 2026

(1) Incorporated by reference to the Current Report on Form 6-K filed on July 22, 2025

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: March 26, 2026

	Aptorum Group Limited
	By:	/s/ Ian Huen
		Ian Huen
		Chief Executive Officer

FAQ

What did Aptorum Group (APM) disclose in its March 2026 Form 6-K/A?

Aptorum Group disclosed an amendment extending the termination date for its planned merger with DiamiR Biosciences to June 30, 2026. It also extended related services and licensing agreements and filed the amendment as an exhibit for investors to review.

What is the new termination date for the Aptorum–DiamiR merger?

The new termination date for the Aptorum–DiamiR merger is June 30, 2026. This replaces the original December 31, 2025 cutoff, giving both parties more time to satisfy closing conditions before deciding whether the planned combination will be completed.

Which agreements between Aptorum and DiamiR were extended to June 30, 2026?

The Management Services Agreement and the Intellectual Property License Agreement tied to the Aptorum–DiamiR merger were both extended to June 30, 2026. An amendment to the Management Services Agreement reflecting the new term was executed and filed as an exhibit for reference.

How is Aptorum Group (APM) advancing shareholder approval for the DiamiR merger?

Aptorum has filed a registration statement on Form S-4 related to the merger and plans to mail shareholder meeting notices. Shareholders of record will receive detailed materials and proxy information to vote on approving the proposed combination and related transactions.

Does the Aptorum Form 6-K/A constitute an offer to sell securities?

The Form 6-K/A explicitly states it does not constitute an offer to sell or a solicitation to buy any securities. Any securities offering related to the merger will occur only under a proper prospectus that meets Section 10 of the Securities Act of 1933.

Where can investors access Aptorum’s S-4 for the DiamiR merger?

Investors can access Aptorum’s Form S-4 registration statement on the SEC’s website at www.sec.gov. Once available, shareholder notices and related documents may also be requested from Aptorum’s principal office at 17 Hanover Square, London, attention to the named contact.

Filing Exhibits & Attachments

1 document

Agreements & Contracts

• EX-10.3 AMENDMENT TO THE MANAGEMENT SERVICES AGREEMENT DATED AS OF MARCH 10, 2026 7.1 KB