🕵️ Gossamer BIO, Inc. ($GOSS)
SEC insider & ownership activity, last 12 months · CIK 1728117 · every row links its SEC filing
Over the last 12 months insiders bought $50K with no open-market selling against it. Milligan Sandra bought $50K in discretionary trades (Aug). Blackrock, Inc. added 5.3% → 6.5%. One red-flag 8-K in the window: Delisting notice (3.01), Apr 8, 2026.
Monthly net open-market insider flow, last 12 months (up = net buying)
Insider flow
1 buyer, $50K (1 lots) · 0 sellers, $0 (0 lots)
| Insider | Buys | Bought | Sells | Sold | Last |
|---|---|---|---|---|---|
| Milligan Sandra | 1 | $50K | 0 | – | Aug 19, 2025 |
5%+ holders
| Holder | Stake | Class | Schedule | Event | |
|---|---|---|---|---|---|
| 683 Capital Management, LLC | 10.0% | 13G | Jun 11, 2026 | filing ↗ | |
| 683 Capital Partners, LP | 10.0% | 13G | Jun 11, 2026 | filing ↗ | |
| Ari Zweiman | 10.0% | 13G | Jun 11, 2026 | filing ↗ | |
| Context Capital Management, LLC | 9.9% | 13G | Jun 9, 2026 | filing ↗ | |
| Michael S. Rosen | 9.9% | 13G | Jun 9, 2026 | filing ↗ | |
| William D. Fertig | 9.9% | 13G | Jun 9, 2026 | filing ↗ | |
| Charles E. Carnegie | 9.9% | 13G | Jun 9, 2026 | filing ↗ | |
| Context Partners Master Fund, L.P. | 9.9% | 13G | Jun 9, 2026 | filing ↗ | |
| Octagon Investments Master Fund | 8.6% | 13G | Feb 5, 2025 | filing ↗ | |
| Deepcurrents Investment Group LLC | 7.7% | 13G | Jun 11, 2026 | filing ↗ | |
| Kai Zheng | 7.7% | 13G | Jun 11, 2026 | filing ↗ | |
| D. E. SHAW & Co., L.P. | 7.1% | 13D | Jul 22, 2026 | filing ↗ | |
| David E. Shaw | 7.1% | 13D | Jul 22, 2026 | filing ↗ | |
| D. E. SHAW & Co., L.L.C. | 7.0% | 13D | Jul 22, 2026 | filing ↗ | |
| D. E. SHAW Valence Portfolios, L.L.C. | 6.7% | 13D | Jul 22, 2026 | filing ↗ | |
| Blackrock, Inc. | 6.5% | 13G | Jan 21, 2026 | filing ↗ | |
| DCIG GP LLC | 5.7% | 13G | Jun 11, 2026 | filing ↗ | |
| DCIG Capital Master Fund LP | 5.7% | 13G | Jun 11, 2026 | filing ↗ |
Planned insider sales (Form 144)
No sale notices filed in the last 12 months.
Material events (8-K)
| Item | Event date | |
|---|---|---|
| Material agreement (1.01) | Jul 23, 2026 | filing ↗ |
| Agreement terminated (1.02) | Jul 23, 2026 | filing ↗ |
| Earnings (2.02) | Jul 23, 2026 | filing ↗ |
| Reg FD disclosure (7.01) | Jul 23, 2026 | filing ↗ |
| Other events (8.01) | Jul 23, 2026 | filing ↗ |
| Financial Statements and Exhibits (9.01) | Jul 23, 2026 | filing ↗ |
| Officer/director changes (5.02) | Jul 14, 2026 | filing ↗ |
| Charter/bylaw changes (5.03) | Jul 14, 2026 | filing ↗ |
| Shareholder vote (5.07) | Jul 14, 2026 | filing ↗ |
| Financial Statements and Exhibits (9.01) | Jul 14, 2026 | filing ↗ |
| Reg FD disclosure (7.01) | Jul 1, 2026 | filing ↗ |
| Financial Statements and Exhibits (9.01) | Jul 1, 2026 | filing ↗ |
| Reg FD disclosure (7.01) | Jun 17, 2026 | filing ↗ |
| Financial Statements and Exhibits (9.01) | Jun 17, 2026 | filing ↗ |
| Shareholder vote (5.07) | Jun 4, 2026 | filing ↗ |
| Material agreement (1.01) | Jun 3, 2026 | filing ↗ |
| Agreement terminated (1.02) | Jun 3, 2026 | filing ↗ |
| New financial obligation (2.03) | Jun 3, 2026 | filing ↗ |
| Unregistered equity sale (3.02) | Jun 3, 2026 | filing ↗ |
| Reg FD disclosure (7.01) | Jun 3, 2026 | filing ↗ |
| Financial Statements and Exhibits (9.01) | Jun 3, 2026 | filing ↗ |
| Other events (8.01) | Jun 2, 2026 | filing ↗ |
| Financial Statements and Exhibits (9.01) | Jun 2, 2026 | filing ↗ |
| Material agreement (1.01) | May 18, 2026 | filing ↗ |
| Earnings (2.02) | May 18, 2026 | filing ↗ |
| Officer/director changes (5.02) | May 18, 2026 | filing ↗ |
| Reg FD disclosure (7.01) | May 18, 2026 | filing ↗ |
| Other events (8.01) | May 18, 2026 | filing ↗ |
| Delisting notice (3.01) | Apr 8, 2026 | filing ↗ |
| Earnings (2.02) | Mar 17, 2026 | filing ↗ |