Companies / Seaport Therapeutics, Inc.
Seaport Therapeutics, Inc.
Nasdaq: SPTXCIK 2042347BOSTON, MA
Ownership
53.5M shares outstanding · as of Jul 27, 2026
Ownership
| Insiders | 6.71% | 3,594,569 |
| 10%+ / strategic | 11.76% | 6,294,951 |
| Institutions | 0.43% | 229,863 |
| Public float | 81.10% | 43,411,167 |
% of common shares outstanding (exact, from the latest cover-page filing). Institutions are quarterly 13F snapshots; insiders reflect current officers & directors.
Insiders 24
View all →| Insider | % of shares | Shares |
|---|---|---|
ARCH Venture Partners XII, LLC10% owner | 11.76% | 6,294,951 |
Healy JamesDirector | 5.10% | 2,731,538 |
Paul Steven MDirector | 1.61% | 863,031 |
ARCH Venture Fund XII, L.P.10% owner | — | — |
ARCH Venture Partners XII, L.P.10% owner | — | — |
Burow Kristina10% owner | — | — |
Crandell Keith10% owner | — | — |
GAP (Bermuda) L.P.Director · 10% owner | — | — |
GAP Coinvestments CDA, L.P.Director · 10% owner | — | — |
Gap Coinvestments III, LLCDirector · 10% owner | — | — |
Institutional holders 1
View all →| Holder | Value | % of shares |
|---|---|---|
| $4.99M | 0.43% |
Activity
InsidersInstitutions
What insiders are doing in this stock (Form 4).| Date | Actor | Action | Security | Value | Shares Δ | Position after | Impact |
|---|---|---|---|---|---|---|---|
| May 4, 2026 | ARCH Venture Partners XII, LLC 10% owner | Buy | Common Stock | $19.80M | +1.1M +21.17% | 6,294,951 11.76% of shares | high |
| May 4, 2026 | Healy James Director | Other | Series B Preferred Stock | — | -2.5M -100.00% | 0 0.00% of shares | low |
| May 4, 2026 | Healy James Director | Other | Series A-2 Preferred Stock | — | -6.1M -100.00% | 0 0.00% of shares | low |
| May 4, 2026 | Healy James Director | Other | Common Stock | — | +804K +41.74% | 2,731,538 5.10% of shares | low |
| May 4, 2026 | Healy James Director | Other | Common Stock | — | +1.9M | 1,927,159 3.60% of shares | low |
| May 4, 2026 | Paul Steven M Director | Other | Series B Preferred Stock | — | -211K -100.00% | 0 0.00% of shares | low |
| Apr 30, 2026 | Paul Steven M Director | Grant | Stock Option (Right to Buy) | — | +991K | 991,192 1.85% of shares | low |
| Apr 30, 2026 | Paul Steven M Director | Grant | Stock Option (Right to Buy) | — | +12K | 12,258 0.02% of shares | low |
Securities
via CUSIP / OpenFIGI
| Symbol | Type | CUSIP |
|---|---|---|
| SPTX | Common Stock | 81221K108 |