QNTM files Form 6-K/A to replace incorrect Exhibit 99.1

Rhea-AI Filing Summary

Quantum Biopharma Ltd. filed an amended Form 6‑K to correct an exhibit previously furnished. The company states that an incorrect version of Exhibit 99.1 accompanied its April 16, 2024 submission, and this amendment is furnished solely to provide the correct exhibit.

The amendment does not modify or update other disclosures from the original report. The corrected Exhibit 99.1 is titled “Press Release dated April 1, 2024 - FSD Pharma Announces Filing of Year-End 2023 Results.”

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K/A

Amendment No. 1

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

OF THE SECURITIES EXCHANGE ACT OF 1934

For the month of October 2025

Commission File Number: 001-39152

QUANTUM BIOPHARMA LTD.

(Registrant)

1 Adelaide Street East, Suite 801

Toronto, Ontario M5C 2V9

(Address of Principal Executive Offices)

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  ☐

Indicate by check mark if the Registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ☐

Indicate by check mark if the Registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ☐

EXPLANATORY NOTE

On April 16, 2024, Quantum Biopharma Ltd. (the "Company") furnished a report on Form 6-K, Accession No. 0001654954-24-004643 (the "Original Report"). Due to an administrative error, an incorrect version of Exhibit 99.1 was furnished with the Original Report. This Amendment No. 1 to the Original Report on Form 6-K (this "Amendment") is being furnished solely to furnish the correct version of Exhibit 99.1. Except as specifically described in this explanatory note, this Amendment does not reflect events that may have occurred subsequent to the original submission date and does not modify or update in any way the disclosures made in the Original Report.

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.

	QUANTUM BIOPHARMA LTD.
	(Registrant)
Date October 28, 2025	By	/s/ Donal Carroll
		Donal Carroll
		Chief Financial Officer

EXHIBIT INDEX

Exhibit		Description of Exhibit
99.1		Press Release dated April 1, 2024 - FSD Pharma Announces Filing of Year-End 2023 Results

FAQ

What did QNTM file?

An amended Form 6‑K/A to correct a previously furnished exhibit.

Why was this amendment necessary for QNTM?

Due to an administrative error, the wrong version of Exhibit 99.1 was furnished with the April 16, 2024 submission.

Which exhibit was corrected in QNTM’s filing?

Exhibit 99.1, identified as “Press Release dated April 1, 2024 - FSD Pharma Announces Filing of Year-End 2023 Results.”

Does the amendment change other disclosures for QNTM?

No. It is furnished solely to provide the correct Exhibit 99.1 and does not modify other disclosures.

Who signed the QNTM amendment and when?

It was signed by Donal Carroll, Chief Financial Officer, dated October 28, 2025.

When was the original QNTM 6-K furnished?

The original was furnished on April 16, 2024 (Accession No. 0001654954-24-004643).