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424B5 1 tm2530369-3_424b5.htm 424B5 tm2530369-3_424b5 - none - 5.0207244s

Filed Pursuant to Rule 424(b)(5)
Registration No. 333-287622

PROSPECTUS SUPPLEMENT
(To Prospectus Dated November 26, 2025)

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$35,530,980.56

Common Stock

On September 6, 2024, we entered into an Equity Distribution Agreement, or the Distribution Agreement, with Oppenheimer & Co. Inc., or Oppenheimer, relating to our common stock having an aggregate offering price of up to $50 million. On September 6, 2024, pursuant to the Distribution Agreement, we filed a prospectus supplement pursuant to which we could offer and sell from time to time shares of our common stock having an aggregate offering price of up to $50 million through Oppenheimer. As of November 28, 2025, of the $50 million of our common stock covered by the Distribution Agreement and the related prospectus supplement, dated September 6, 2024 to the Company’s Registration Statement on Form S-3 (333-265061), we have issued and sold an aggregate of 6,393,341 shares of our common stock for gross proceeds of $14,469,019.44.

With the filing of this prospectus supplement, we are replacing and superseding the prior prospectus supplement, and all sales of our common stock pursuant to the Distribution Agreement shall be pursuant to this prospectus supplement and the accompanying base prospectus. This prospectus supplement and the accompanying base prospectus, which together we sometimes refer to as the prospectus, relates to the offer and sale, from time to time, of shares of our common stock having an aggregate gross sales price of up to $35,530,980.56 through Oppenheimer in accordance with the terms of the Distribution Agreement.

Our common stock is listed on The Nasdaq Global Market, or Nasdaq, under the symbol “GANX.” On November 26, 2025, the closing sale price of our common stock on Nasdaq was $3.14 per share.

Sales of our common stock, if any, under this prospectus supplement may be made by any method deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended, or the Securities Act. Oppenheimer is not required to sell any specific number or dollar amount of securities, but will act as our sales agent, using commercially reasonable efforts to sell on our behalf all of the shares of common stock requested to be sold by us, consistent with its normal trading and sales practices, on mutually agreed terms between Oppenheimer and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

The compensation to Oppenheimer for sales of common stock sold pursuant to the Distribution Agreement will be an amount equal to 3.0% of the gross proceeds of any shares of common stock sold under the Distribution Agreement. See “Plan of Distribution” for additional information regarding the compensation to be paid to Oppenheimer. The net proceeds from any sales under this prospectus supplement will be used as described under “Use of Proceeds.” The proceeds we receive from sales of our common stock, if any, will depend on the number of shares actually sold and the offering price of such shares.

In connection with the sale of the common stock on our behalf, Oppenheimer will be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of Oppenheimer will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to Oppenheimer with respect to certain liabilities, including liabilities under the Securities Act or the Securities Exchange Act of 1934, as amended, or the Exchange Act.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading “Risk Factors” on page S-7 of this prospectus supplement and under similar headings in the other documents that are incorporated by reference into this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

Oppenheimer & Co.

The date of this prospectus supplement is November 28, 2025.

	ABOUT THIS PROSPECTUS SUPPLEMENT					S-1
	SUMMARY					S-3
	RISK FACTORS					S-7
	SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS					S-10
	USE OF PROCEEDS					S-12
	DILUTION					S-14
	PLAN OF DISTRIBUTION					S-15
	LEGAL MATTERS					S-16
	EXPERTS					S-16
	WHERE YOU CAN FIND MORE INFORMATION					S-17
	INCORPORATION OF CERTAIN INFORMATION BY REFERENCE					S-17

	ABOUT THIS PROSPECTUS					1
	PROSPECTUS SUMMARY					2
	RISK FACTORS					5
	CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS					6
	USE OF PROCEEDS					8
	THE SECURITIES WE MAY OFFER					9
	DESCRIPTION OF CAPITAL STOCK					10
	DESCRIPTION OF WARRANTS					14
	DESCRIPTION OF DEBT SECURITIES					15
	DESCRIPTION OF SUBSCRIPTION RIGHTS					21
	DESCRIPTION OF UNITS					22
	FORMS OF SECURITIES					23
	PLAN OF DISTRIBUTION					25
	LEGAL MATTERS					29
	EXPERTS					29
	ADDITIONAL INFORMATION					30
	INCORPORATION OF CERTAIN INFORMATION BY REFERENCE					31

Assumed public offering price per share			$	3.14
Net tangible book value per share of as September 30, 2025	$	0.12
Increase in net tangible book value per share attributable to this offering	$	0.72
As adjusted net tangible book value per share as of September 30, 2025, after giving effect to this offering			$	0.84
Dilution per share to new investors			$	2.30

SEC Form 424B5 filed by Gain Therapeutics Inc.