As of November 6, 2026, 6 holders' latest Schedule 13D or 13G filings report owning 5% or more of Seaport Therapeutics, Inc. The largest reported stake is PureTech Health plc's, at 31.2%. 6 filings are on record since May 6, 2026 (Schedule 13G, August 14, 2026).
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Key facts
- · Reporting person: PureTech Health plc · Sole voting: 0 · Shared voting: 16,685,013 · Sole dispositive: 0 · Shared dispositive: 16,685,013 · SCHEDULE 13G, 2026-08-14
- · Reporting person: Zohar Daphne · Sole voting: 5,225,497 · Shared voting: 0 · Sole dispositive: 5,225,497 · Shared dispositive: 0 · SCHEDULE 13G, 2026-08-05
- · Reporting person: Paul Steven M · Sole voting: 3,516,718 · Shared voting: 0 · Sole dispositive: 3,516,718 · Shared dispositive: 0 · SCHEDULE 13G, 2026-08-05
- · Holder: The Goldman Sachs Group, Inc. · Percent: 5.5% · SCHEDULE 13G
- · Holder: General Atlantic, L.P. · Percent: 11.5% · SCHEDULE 13D
Seaport Therapeutics, Inc. has 6 Schedule 13D or 13G filings on record since 2026-05-06. 6 holders' latest filing reports 5% or more of voting common stock, $0.001 par value per share. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| PureTech Health plc | 31.2% | 16,685,013 | SCHEDULE 13G, 2026-08-14 | 2026-06-30 |
| ARCH Venture Fund XII, L.P. | 11.9% | 6,294,951 | SCHEDULE 13D, 2026-05-06 | 2026-05-04 |
| General Atlantic, L.P. | 11.5% | 6,101,582 | SCHEDULE 13D, 2026-05-11 | 2026-05-04 |
| 9.1% | 5,225,497 | SCHEDULE 13G, 2026-08-05 | 2026-06-30 | |
| 6.3% | 3,516,718 | SCHEDULE 13G, 2026-08-05 | 2026-06-30 | |
| The Goldman Sachs Group, Inc. | 5.5% | 2,791,814 | SCHEDULE 13G, 2026-05-11 | 2026-05-06 |
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More on Seaport Therapeutics, Inc. and the records around it.
Seaport Therapeutics, Inc. elsewhere on the record
Companies that share a holder
- ARCH Venture Fund XII, L.P. also filed stake reports on 5 other companies: City Therapeutics, Inc. (Oct 2026), Parabilis Medicines, Inc. (Aug 2026), Neumora Therapeutics, Inc. (Apr 2026)
- General Atlantic, L.P. also filed stake reports on 10 other companies: Korsana Biosciences, Inc. (Sep 2026), dLocal Ltd (Aug 2026), Pharvaris N.V. (Aug 2026)
- THE GOLDMAN SACHS GROUP, INC. also filed stake reports on 173 other companies: AEON ACQUISITION I CORP. (Nov 2026), ALPEX ACQUISITION CORPORATION (Nov 2026), ARCHIMEDES TECH SPAC PARTNERS II CO. (Nov 2026)
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| PureTech Health plc | 0 | 16,685,013 | 0 | 16,685,013 | SCHEDULE 13G, 2026-08-14 |
| PureTech Health LLC | 0 | 16,685,013 | 0 | 16,685,013 | SCHEDULE 13G, 2026-08-14 |
| PureTech LYT, Inc. | 0 | 16,685,013 | 0 | 16,685,013 | SCHEDULE 13G, 2026-08-14 |
| Zohar Daphne | 5,225,497 | 0 | 5,225,497 | 0 | SCHEDULE 13G, 2026-08-05 |
| Paul Steven M | 3,516,718 | 0 | 3,516,718 | 0 | SCHEDULE 13G, 2026-08-05 |
The latest filing identifies Seaport Therapeutics, Inc. by CUSIP 81221K108 and gives its principal executive office as 101 Seaport Blvd., Floor 12, Boston, MA 02210 (SCHEDULE 13G, 2026-08-14).
Purpose of Transaction (Item 4)
ARCH Venture Fund XII, L.P.
AVF XII and the other Reporting Persons acquired the Common Stock for investment purposes. Depending on market conditions, the continuing evaluation of the business and prospects of the Issuer and other factors, AVF XII and other Reporting Persons may dispose of or acquire additional shares of Common Stock of the Issuer. Except as set forth above, none of the Reporting Persons has any present plans which relate to or would result in the matters set forth in subparagraphs (a) - (j) of Item 4 of Schedule 13D.Item 4 of the SCHEDULE 13D filed 2026-05-06
General Atlantic, L.P.
The Reporting Persons acquired the common stock reported herein for investment purposes. Consistent with such purposes, the Reporting Persons may engage in communications with, without limitation, one or more shareholders of the Company, management of the Company, one or more members of the board of directors of the Company, and may make suggestions concerning the Company's operations, prospects, business and financial strategies, strategic transactions, assets and liabilities, business and financing alternatives, the composition of the board of directors of the Company and such other matters as the Reporting Persons may deem relevant to their investment in the common stock. The Reporting Persons expect that they will, from time to time, review their investment position in the common stock or the Company and may, depending on the Company's performance and other market conditions, increase or decrease their investment position in the common stock. The Reporting Persons may, from time to time, make additional purchases of common stock either in the open market or in privately-negotiated transactions, depending upon the Reporting Persons' evaluation of the Company's business, prospects and financial condition, the market for the common stock, other opportunities available to the Reporting Persons, general economic conditions, stock market conditions and other factors. Depending upon the factors noted above, the Reporting Persons may also decide to hold or dispose of all or …The first part of Item 4 of the SCHEDULE 13D filed 2026-05-11; the filing has the rest
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2026-05-06 | ARCH Venture Fund XII, L.P. | 11.9% | SCHEDULE 13D |
| 2026-05-11 | The Goldman Sachs Group, Inc. | 5.5% | SCHEDULE 13G |
| 2026-05-11 | General Atlantic, L.P. | 11.5% | SCHEDULE 13D |
| 2026-08-05 | Paul Steven M | 6.3% | SCHEDULE 13G |
| 2026-08-05 | Zohar Daphne | 9.1% | SCHEDULE 13G |
| 2026-08-14 | PureTech Health plc | 31.2% | SCHEDULE 13G |
Questions about who owns Seaport Therapeutics, Inc.
Who owns Seaport Therapeutics, Inc.?
On this page, 6 holders' latest ownership filings report 5% or more of Seaport Therapeutics, Inc.: PureTech Health plc (31.2%, Schedule 13G, filed 2026-08-14), ARCH Venture Fund XII, L.P. (11.9%, Schedule 13D, filed 2026-05-06), General Atlantic, L.P. (11.5%, Schedule 13D, filed 2026-05-11), Zohar Daphne (9.1%, Schedule 13G, filed 2026-08-05) and Paul Steven M (6.3%, Schedule 13G, filed 2026-08-05); 1 more is listed above.
Who are the largest shareholders of Seaport Therapeutics, Inc.?
By the share each holder's latest filing reports, the largest holders of Seaport Therapeutics, Inc. on this page are PureTech Health plc (31.2%), ARCH Venture Fund XII, L.P. (11.9%) and General Atlantic, L.P. (11.5%).
When did PureTech Health plc buy into Seaport Therapeutics, Inc.?
The filings give report dates, not purchase dates. The earliest filing from PureTech Health plc on this page is the Schedule 13G, filed 2026-08-14, reporting 31.2%.
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 Seaport Therapeutics, Inc.
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| May 1, 2026 | IPO filing, Form 424B4 | $18 a share | IPO filings | Source |
| April 27, 2026 | IPO filing, Form S-1/A | — | IPO filings | Source |
| April 10, 2026 | IPO filing, Form S-1 | — | IPO filings | 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.