As of November 6, 2026, 5 holders' latest Schedule 13D or 13G filings report owning 5% or more of Adagio Medical Holdings, Inc. The largest reported stake is Perceptive Advisors LLC's, at 55.4%. 12 filings are on record since August 12, 2025 (Schedule 13G/A, May 15, 2026).
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Key facts
- · Reporting person: ADAR1 Capital Management, LLC · Sole voting: 0 · Shared voting: 1,205,447 · Sole dispositive: 0 · Shared dispositive: 1,205,447 · SCHEDULE 13G/A, 2026-08-14
- · Reporting person: Sio Capital Management, LLC · Sole voting: 0 · Shared voting: 698,989 · Sole dispositive: 0 · Shared dispositive: 698,989 · SCHEDULE 13G/A, 2026-07-28
- · Reporting person: Perceptive Advisors LLC · Sole voting: 0 · Shared voting: 15,321,655 · Sole dispositive: 0 · Shared dispositive: 15,321,655 · SCHEDULE 13G/A, 2026-05-15
- · Reporting person: Adage Capital Management, L.P. · Sole voting: 0 · Shared voting: 1,258,501 · Sole dispositive: 0 · Shared dispositive: 1,258,501 · SCHEDULE 13G/A, 2026-05-13
- · Holder: ADAR1 Capital Management, LLC · Percent: 5.7% · SCHEDULE 13G
Adagio Medical Holdings, Inc. has 12 Schedule 13D or 13G filings on record since 2025-08-12. 5 holders' latest filing reports 5% or more of common stock, par value $0.0001 per share. Each figure below is the holder's own, as filed, with the filing linked.
Layoffs on record: about 43 jobs, latest 2026-09-23 (layoff filings and notices).
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Perceptive Advisors LLC | 55.4% | 15,321,655 | SCHEDULE 13G/A, 2026-05-15 | 2026-03-31 |
| Alyeska Investment Group, L.P. | 9.9% | 2,096,784 | SCHEDULE 13G, 2026-02-17 | 2025-12-31 |
| RA Capital Management, L.P. | 7.2% | 1,200,000 | SCHEDULE 13G/A, 2025-08-26 | 2025-06-30 |
| Adage Capital Management, L.P. | 5.67% | 1,258,501 | SCHEDULE 13G/A, 2026-05-13 | 2026-03-31 |
| ADAR1 Capital Management, LLC | 5.4% | 1,205,447 | SCHEDULE 13G/A, 2026-08-14 | 2026-06-30 |
| Sio Capital Management, LLC | 3.15% | 698,989 | SCHEDULE 13G/A, 2026-07-28 | 2026-06-30 |
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More on Adagio Medical Holdings, Inc. and the records around it.
Adagio Medical Holdings, Inc. elsewhere on the record
- Layoff notices Sep 2026
- Form D filing Oct 2025
- Who owns it
Companies that share a holder
- Sio Capital Management, LLC also filed stake reports on 9 other companies: Enveric Biosciences, Inc. (Nov 2026), PMV Pharmaceuticals, Inc. (Jul 2026), Anteris Technologies Global Corp. (May 2026)
- ADAR1 Capital Management, LLC also filed stake reports on 29 other companies: InMed Pharmaceuticals, Inc. (Oct 2026), Tenax Therapeutics, Inc. (Sep 2026), Amanat Acquisition Corp. (Aug 2026)
- Perceptive Advisors LLC also filed stake reports on 57 other companies: Nautilus Biotechnology, Inc. (Nov 2026), Athira Pharma, Inc. (Oct 2026), IRulya Therapeutics Inc. (Oct 2026)
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Perceptive Advisors LLC | 0 | 15,321,655 | 0 | 15,321,655 | SCHEDULE 13G/A, 2026-05-15 |
| Joseph Edelman | 0 | 15,321,655 | 0 | 15,321,655 | SCHEDULE 13G/A, 2026-05-15 |
| Perceptive Life Sciences Master Fund, Ltd. | 0 | 15,120,753 | 0 | 15,120,753 | SCHEDULE 13G/A, 2026-05-15 |
| C2 Life Sciences LLC | 0 | 200,902 | 0 | 200,902 | SCHEDULE 13G/A, 2026-05-15 |
| Adage Capital Management, L.P. | 0 | 1,258,501 | 0 | 1,258,501 | SCHEDULE 13G/A, 2026-05-13 |
| Robert Atchinson | 0 | 1,258,501 | 0 | 1,258,501 | SCHEDULE 13G/A, 2026-05-13 |
| Phillip Gross | 0 | 1,258,501 | 0 | 1,258,501 | SCHEDULE 13G/A, 2026-05-13 |
| ADAR1 Capital Management, LLC | 0 | 1,205,447 | 0 | 1,205,447 | SCHEDULE 13G/A, 2026-08-14 |
| Daniel Schneeberger | 0 | 1,205,447 | 0 | 1,205,447 | SCHEDULE 13G/A, 2026-08-14 |
| Sio Capital Management, LLC | 0 | 698,989 | 0 | 698,989 | SCHEDULE 13G/A, 2026-07-28 |
The latest filing identifies Adagio Medical Holdings, Inc. by CUSIP 00534B100 and gives its principal executive office as 26051 Merit Circle, Suite 102, Laguna Hills, CA 92653 (SCHEDULE 13G/A, 2026-08-14).
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-12 | Adage Capital Management, L.P. | 5.34% | SCHEDULE 13G |
| 2025-08-14 | RA Capital Management, L.P. | 0% | SCHEDULE 13G/A |
| 2025-08-26 | RA Capital Management, L.P. | 7.2% | SCHEDULE 13G/A |
| 2025-11-13 | Adage Capital Management, L.P. | 6.88% | SCHEDULE 13G/A |
| 2026-02-11 | Sio Capital Management, LLC | 6.08% | SCHEDULE 13G |
| 2026-02-17 | ADAR1 Capital Management, LLC | 5.7% | SCHEDULE 13G |
| 2026-02-17 | Alyeska Investment Group, L.P. | 9.9% | SCHEDULE 13G |
| 2026-02-17 | Perceptive Advisors LLC | 57.5% | SCHEDULE 13G/A |
| 2026-05-13 | Adage Capital Management, L.P. | 5.67% | SCHEDULE 13G/A |
| 2026-05-15 | Perceptive Advisors LLC | 55.4% | SCHEDULE 13G/A |
| 2026-07-28 | Sio Capital Management, LLC | 3.15% | SCHEDULE 13G/A |
| 2026-08-14 | ADAR1 Capital Management, LLC | 5.4% | SCHEDULE 13G/A |
Questions about who owns Adagio Medical Holdings, Inc.
Who owns Adagio Medical Holdings, Inc.?
On this page, 5 holders' latest ownership filings report 5% or more of Adagio Medical Holdings, Inc.: Perceptive Advisors LLC (55.4%, Schedule 13G/A, filed 2026-05-15), Alyeska Investment Group, L.P. (9.9%, Schedule 13G, filed 2026-02-17), RA Capital Management, L.P. (7.2%, Schedule 13G/A, filed 2025-08-26), Adage Capital Management, L.P. (5.67%, Schedule 13G/A, filed 2026-05-13) and ADAR1 Capital Management, LLC (5.4%, Schedule 13G/A, filed 2026-08-14).
Who are the largest shareholders of Adagio Medical Holdings, Inc.?
By the share each holder's latest filing reports, the largest holders of Adagio Medical Holdings, Inc. on this page are Perceptive Advisors LLC (55.4%), Alyeska Investment Group, L.P. (9.9%) and RA Capital Management, L.P. (7.2%).
When did Perceptive Advisors LLC buy into Adagio Medical Holdings, Inc.?
The filings give report dates, not purchase dates. The earliest filing from Perceptive Advisors LLC on this page is the Schedule 13G/A, filed 2026-02-17, reporting 57.5%; its latest, Schedule 13G/A filed 2026-05-15, reports 55.4%. That earliest filing is itself an amendment, which updates an earlier report.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 12 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
Also on the record for Adagio Medical Holdings, Inc.
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| October 29, 2025 | Form D, private offering | $19M sold | Form D page | Source |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.