Company: GANX
Filing Date: 2025-11-28
Form Type: 424B5
Source: 0001104659-25-116944
Chunk: 9

Company: Gain Therapeutics, Inc.
Filing Date: 2025-11-28
Form: 424B5
Chunk 9
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 incorporated by reference into this prospectus supplement.

Nasdaq Global Market 
 symbol

“GANX”

The number of shares of our common stock to be outstanding immediately after this offering is based on 38,462,085 shares of our common stock outstanding as of November 26, 2025, and excludes:

•

7,421,521 shares of common stock issuable upon the exercise of outstanding warrants to purchase shares of common stock with a weighted-average exercise price of $2.27 per share;

•

24,169 shares of common stock issuable upon the vesting of outstanding restricted stock units;

•

3,619,730 shares issuable upon the exercise of outstanding stock options with a weighted-average exercise price of $3.62 per share; and

•

2,065,215 shares reserved for future issuances under our equity compensation plans.

Except as otherwise indicated, the information in this prospectus supplement assumes no exercise of the outstanding stock options or warrants described above.

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TABLE OF CONTENTS

### RISK FACTORS
An investment in our common stock involves a high degree of risk. Before deciding whether to invest in our common stock, you should carefully consider the risks described below and those discussed under the section titled “Risk Factors” contained in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024as updated by our other reports and documents that are incorporated by reference into this prospectus supplement and the accompanying prospectus, before deciding whether to purchase any of the securities being registered pursuant to the registration statement of which this prospectus supplement is a part. Each of the risk factors could adversely affect our business, results of operations, financial condition and cash flows, as well as adversely affect the value of an investment in our securities, and the occurrence of any of these risks might cause you to lose all or part of your investment. Additional risks not presently known to us or that we currently believe are immaterial may also significantly impair our business operations. Please also read carefully the section below titled “Special Note Regarding Forward-Looking Statements.”

#### Risks Related to this Offering
We will have broad discretion as to the use of the net proceeds from this offering and may not use the net proceeds effectively.

We currently intend to use the net proceeds from this offering for working capital and general corporate purposes. However, we have not determined the specific allocation of the net proceeds among these potential uses and have not designated the amount of net proceeds from this offering to be