SEC Form 424B3 filed by Adagio Medical Holdings Inc

Filed Pursuant to Rule 424(b)(3)

Registration No. 333-284263

PROSPECTUS SUPPLEMENT

To Prospectus dated February 7, 2025

Up to 73,333 Shares of Common Stock

Up to 31,145,319 Shares of Common Stock Issuable Upon Conversion of Notes

Up to 600,000 Shares of Common Stock Issuable Upon Exercise of Warrants

Adagio Medical Holdings, Inc.

This prospectus supplement updates and supplements the information contained in the prospectus dated February 7, 2025 (as may be supplemented or amended from time to time, the “Prospectus”), which forms part of our registration statement on Form S-1 (File No. 333-284263) with the information contained in our Current Report on Form 8-K that was filed with the Securities and Exchange Commission on December 16, 2025 (the “Current Report”). Accordingly, we have attached the Current Report to this prospectus supplement.

The Prospectus and this prospectus supplement relate to the offer, sale or other disposition from time to time of up to 31,818,652 shares of our common stock, $0.0001 par value per share (the “Common Stock”), by the selling stockholders named in this prospectus or their permitted transferees (the “selling stockholders”), consisting of (i) 73,333 shares of Common Stock (the “Registration Delay Shares”) issued pursuant to the terms of the Convert Waivers (as defined below), (ii) up to 31,145,319 shares of Common Stock (excluding the shares of Common Stock underlying the Warrants (as defined below)) (the “Convertible Note Shares”) issuable upon the conversion of those certain 13% senior secured convertible notes, with a conversion price of $10.00 per share, subject to adjustment (the “Convertible Notes”) issuable pursuant to that certain securities purchase agreement, dated February 13, 2024, by and among us and those certain investors (the “Convert Investors”), and any assignment thereunder (the “Convertible Security Subscription Agreement”), and that certain note purchase agreement, dated February 13, 2024, by and among us, Adagio Medical, Inc., a Delaware corporation, and that certain investor party thereto, and (iii) up to 600,000 shares of Common Stock (the “Warrant Shares”) issuable upon exercise of those warrants to purchase shares of Common Stock, with an exercise price of $24.00 per share (the “Warrants”), issued pursuant to the Convertible Security Subscription Agreement.

You should read this prospectus supplement in conjunction with the Prospectus. This prospectus supplement is qualified by reference to the Prospectus except to the extent that the information in this prospectus supplement supersedes the information contained in the Prospectus. This prospectus supplement is not complete without, and may not be delivered or utilized except in connection with, the Prospectus. If there is any inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement. Terms used in this prospectus supplement but not defined herein shall have the meanings given to such terms in the Prospectus.

Our Common Stock is listed on The Nasdaq Capital Market under the symbol “ADGM”. On December 16, 2025, the last reported sales price of our Common Stock was $1.18 per share.

We are an “emerging growth company” as defined under U.S. federal securities laws and, as such, have elected to comply with reduced public company reporting requirements. This prospectus complies with the requirements that apply to an issuer that is an emerging growth company.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described in the section titled “Risk Factors” beginning on page 10 of the prospectus, and under similar headings in any amendments or supplements to the prospectus.

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 the prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is December 16, 2025.

UNITED STATES 

SECURITIES AND EXCHANGE COMMISSION 

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT 

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): December 15, 2025

ADAGIO MEDICAL HOLDINGS, INC.

(Exact name of registrant as specified in its charter)

(949) 348-1188 

(Registrant’s telephone number, including area code)

Not Applicable 

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 or Rule 12b-2 of the Securities Exchange Act of 1934.

Emerging growth company x

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 13(a) of the Exchange Act. ☐

Item 5.07 Submission of Matters to a Vote of Security Holders.

On December 15, 2025, Adagio Medical Holdings, Inc. (the “Company”) held its 2025 Annual Meeting of Stockholders (the “Annual Meeting”). The stockholders considered two proposals, each of which is described in more detail in the Company’s definitive proxy statement filed with the Securities and Exchange Commission on November 4, 2025 (the “Proxy Statement”). Of the 21,179,637 shares outstanding as of the record date, 13,862,436 shares, or 65.45%, were present or represented by proxy at the Annual Meeting. The final results for each of the matters submitted to the stockholders at the Annual Meeting are as follows:

Proposal No 1: Election of two nominees to serve as directors until the 2028 annual meeting of stockholders and until their respective successors are elected and qualified. The votes were cast as follows:

Both nominees were elected.

Proposal No 2: Ratification of the appointment of WithumSmith+Brown, PC as independent registered public accounting firm for the fiscal year ending December 31, 2025. The votes were cast as follows:

SIGNATURE

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 hereunto duly authorized.

Dated: December 16, 2025