As of November 6, 2026, 2 holders' latest Schedule 13D or 13G filings report owning 5% or more of SeaStar Medical Holding Corporation. The largest reported stake is Mitchell P. Kopin's, at 9.99%. 6 filings are on record since August 13, 2025 (Schedule 13G/A, May 13, 2026).
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Key facts
- · Reporting person: Mitchell P. Kopin · Sole voting: 0 · Shared voting: 443,253 · Sole dispositive: 0 · Shared dispositive: 443,253 · SCHEDULE 13G/A, 2026-05-13
- · Reporting person: Ayrton Capital LLC · Sole voting: 278,436 · Shared voting: 0 · Sole dispositive: 278,436 · Shared dispositive: 0 · SCHEDULE 13G, 2026-05-11
- · Holder: Mitchell P. Kopin · Percent: 9.99% · SCHEDULE 13G/A
- · Holder: Mitchell P. Kopin · Percent: 9.99% · SCHEDULE 13G/A
- · Holder: Armistice Capital, LLC · Percent: 4.99% · SCHEDULE 13G/A
SeaStar Medical Holding Corporation has 6 Schedule 13D or 13G filings on record since 2025-08-13. 2 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.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| 9.99% | 443,253 | SCHEDULE 13G/A, 2026-05-13 | 2026-03-31 | |
| Ayrton Capital LLC | 6.52% | 278,436 | SCHEDULE 13G, 2026-05-11 | 2026-03-31 |
| Armistice Capital, LLC | 4.99% | 1,466,096 | SCHEDULE 13G/A, 2025-08-14 | 2025-06-30 |
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More on SeaStar Medical Holding Corporation and the records around it.
SeaStar Medical Holding Corporation elsewhere on the record
- Company profile and every filing Oct 2026
- Form D filing Oct 2026
- Who owns it
Companies that share a holder
- Ayrton Capital LLC also filed stake reports on 31 other companies: Bluejay Diagnostics, Inc. (Aug 2026), BTC Digital Ltd. (Aug 2026), DEFSEC Technologies Inc. (Aug 2026)
- Mitchell P. Kopin also filed stake reports on 55 other companies: SCWorx Corp. (Sep 2026), NFT Limited (Aug 2026), Silexion Therapeutics Corp (Aug 2026)
- Armistice Capital, LLC also filed stake reports on 120 other companies: Autolus Therapeutics plc (Aug 2026), Bicycle Therapeutics plc (Aug 2026), BioXcel Therapeutics, Inc. (Aug 2026)
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What the Full Report on SeaStar Medical Holding Corporation covers
The Short Answer
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What They Do, And How The Money Works
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Mitchell P. Kopin | 0 | 443,253 | 0 | 443,253 | SCHEDULE 13G/A, 2026-05-13 |
| Daniel B. Asher | 0 | 443,253 | 0 | 443,253 | SCHEDULE 13G/A, 2026-05-13 |
| Intracoastal Capital LLC | 0 | 443,253 | 0 | 443,253 | SCHEDULE 13G/A, 2026-05-13 |
| Ayrton Capital LLC | 278,436 | 0 | 278,436 | 0 | SCHEDULE 13G, 2026-05-11 |
| Alto Opportunity Master Fund, SPC - Segregated Master Portfolio B | 278,436 | 0 | 278,436 | 0 | SCHEDULE 13G, 2026-05-11 |
| Waqas Khatri | 278,436 | 0 | 278,436 | 0 | SCHEDULE 13G, 2026-05-11 |
The latest filing identifies SeaStar Medical Holding Corporation by CUSIP 81256L302 and gives its principal executive office as 3513 Brighton Blvd, Suite 410, Denver, CO 80216 (SCHEDULE 13G/A, 2026-05-13).
What the percentages are based on
The percentages below are based on (i) 3,993,719 shares of Common Stock of the Issuer that were outstanding as of March 24, 2026; and (ii) 278,436 shares of Common Stock issuable on the exercise of the Warrants held by the Reporting Persons. The amount of shares outstanding was based upon a statement in the Issuer's 10-K filing on March 25, 2026.Ayrton Capital LLC, SCHEDULE 13G, 2026-05-11
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-13 | Ayrton Capital LLC | 2.6% | SCHEDULE 13G/A |
| 2025-08-14 | Armistice Capital, LLC | 4.99% | SCHEDULE 13G/A |
| 2025-11-07 | Mitchell P. Kopin | 9.99% | SCHEDULE 13G/A |
| 2026-02-13 | Mitchell P. Kopin | 9.99% | SCHEDULE 13G/A |
| 2026-05-11 | Ayrton Capital LLC | 6.52% | SCHEDULE 13G |
| 2026-05-13 | Mitchell P. Kopin | 9.99% | SCHEDULE 13G/A |
Questions about who owns SeaStar Medical Holding Corporation
Who owns SeaStar Medical Holding Corporation?
On this page, 2 holders' latest ownership filings report 5% or more of SeaStar Medical Holding Corporation: Mitchell P. Kopin (9.99%, Schedule 13G/A, filed 2026-05-13) and Ayrton Capital LLC (6.52%, Schedule 13G, filed 2026-05-11).
Who are the largest shareholders of SeaStar Medical Holding Corporation?
By the share each holder's latest filing reports, the largest holders of SeaStar Medical Holding Corporation on this page are Mitchell P. Kopin (9.99%) and Ayrton Capital LLC (6.52%).
When did Mitchell P. Kopin buy into SeaStar Medical Holding Corporation?
The filings give report dates, not purchase dates. The earliest filing from Mitchell P. Kopin on this page is the Schedule 13G/A, filed 2025-11-07, reporting 9.99%; its latest, Schedule 13G/A filed 2026-05-13, reports 9.99%. 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%); 6 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 SeaStar Medical Holding Corporation
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| October 8, 2026 | Form D, private offering | $3.30M sold | Form D page | Source |
| July 1, 2026 | Leadership change filing (Form 8-K, Item 5.02) | — | Leadership changes | Source |
| June 23, 2026 | Leadership change filing (Form 8-K, Item 5.02) | — | Leadership changes | Source |
SeaStar Medical Holding Corporation: every filing and event
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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.