GBIO (Generation Bio Co. Common Stock)
Insider Trading Activity
Every open-market purchase and sale reported by GBIO officers, directors and 10%+ beneficial owners on SEC Form 4, which must be filed within two business days of the transaction. Sales often reflect scheduled 10b5-1 plans or tax withholding rather than a directional view, so read counts alongside the size and the filer.
Market data may be delayed, incomplete, or inaccurate. Not a recommendation to buy, sell, or hold any security. Verify quotes with your broker before trading. See Terms §17.
| Filed | Insider | Role | Type | Shares | Value |
|---|---|---|---|---|---|
| 2026-02-09 | Ronald Harold Wilfred Cooper | Director | U | — | — |
| 2026-02-09 | Anthony G. Quinn | Director | U | — | — |
| 2026-02-09 | Yalonda Howze | INTERIM CEO AND PRESIDENT | U | — | — |
| 2026-02-09 | Gustav Christensen | Director | U | — | — |
| 2026-02-09 | Catherine Stehman-Breen | Director | U | — | — |
| 2026-02-09 | GEOFF MCDONOUGH | Director | U | — | — |
| 2026-02-09 | Kevin John Conway | CHIEF FINANCIAL OFFICER | U | — | — |
| 2026-02-09 | Dannielle Appelhans | Director | U | — | — |
| 2026-02-09 | Atlas Venture Associates X, LLC | 10%+ Owner | U | — | — |
| 2026-02-09 | JEFFREY M JONAS | Director | D | — | — |
| 2026-02-09 | Donald William Nicholson | Director | U | — | — |
| 2026-02-09 | Jason P Rhodes | Director | U | — | — |
| 2026-02-09 | Charles A Jr Rowland | Director | U | — | — |
| 2026-02-04 | GEOFF MCDONOUGH | Director | MIXED | — | — |
| 2026-02-04 | Yalonda Howze | INTERIM CEO & PRESIDENT | MIXED | — | — |
| 2026-02-04 | Kevin John Conway | Chief Financial Officer | MIXED | — | — |
| 2026-01-16 | Yalonda Howze | CHIEF LEGAL OFFICER | MIXED | — | — |
| 2026-01-16 | Kevin John Conway | Chief Financial Officer | MIXED | — | — |
| 2026-01-16 | GEOFF MCDONOUGH | Director | MIXED | — | — |
| 2025-11-21 | GEOFF MCDONOUGH | Director | MIXED | — | — |
| 2025-10-17 | Phillip Samayoa | CHIEF SCIENTIFIC OFFICER | MIXED | — | — |
| 2025-10-17 | Antoinette Paone | CHIEF OPERATING OFFICER | MIXED | — | — |
| 2025-10-17 | Yalonda Howze | CHIEF LEGAL OFFICER | MIXED | — | — |
| 2025-10-17 | Kevin John Conway | Chief Financial Officer | MIXED | — | — |
| 2025-10-17 | GEOFF MCDONOUGH | PRESIDENT AND CEO | MIXED | — | — |
| 2025-07-17 | Kevin John Conway | Chief Financial Officer | MIXED | — | — |
| 2025-07-17 | Antoinette Paone | CHIEF OPERATING OFFICER | MIXED | — | — |
| 2025-07-17 | Yalonda Howze | CHIEF LEGAL OFFICER | MIXED | — | — |
| 2025-07-17 | GEOFF MCDONOUGH | PRESIDENT AND CEO | MIXED | — | — |
| 2025-07-17 | Phillip Samayoa | CHIEF SCIENTIFIC OFFICER | MIXED | — | — |
| 2025-06-06 | JEFFREY M JONAS | Director | A | — | — |
| 2025-06-06 | Anthony G. Quinn | Director | A | — | — |
| 2025-06-06 | Charles A Jr Rowland | Director | A | — | — |
| 2025-06-06 | Dannielle Appelhans | Director | A | — | — |
| 2025-06-06 | Gustav Christensen | Director | A | — | — |
| 2025-06-06 | Jason P Rhodes | Director | A | — | — |
| 2025-06-06 | Ronald Harold Wilfred Cooper | Director | A | — | — |
| 2025-06-06 | Catherine Stehman-Breen | Director | A | — | — |
| 2025-06-06 | Donald William Nicholson | Director | A | — | — |
| 2025-04-17 | Yalonda Howze | CHIEF LEGAL OFFICER | MIXED | — | — |
| 2025-04-17 | GEOFF MCDONOUGH | PRESIDENT AND CEO | MIXED | — | — |
| 2025-04-17 | Antoinette Paone | CHIEF OPERATING OFFICER | MIXED | — | — |
| 2025-04-17 | Kevin John Conway | Chief Financial Officer | MIXED | — | — |
| 2025-04-17 | Phillip Samayoa | CHIEF SCIENTIFIC OFFICER | MIXED | — | — |
| 2025-01-17 | Antoinette Paone | CHIEF OPERATING OFFICER | MIXED | — | — |
| 2025-01-17 | Kevin John Conway | Chief Financial Officer | MIXED | — | — |
| 2025-01-17 | Phillip Samayoa | CHIEF SCIENTIFIC OFFICER | MIXED | — | — |
| 2025-01-17 | GEOFF MCDONOUGH | PRESIDENT AND CEO | MIXED | — | — |
| 2025-01-17 | Yalonda Howze | CHIEF LEGAL OFFICER | MIXED | — | — |
| 2025-01-14 | Antoinette Paone | CHIEF OPERATING OFFICER | A | — | — |
| Insider | Role | Shares Held | Value |
|---|---|---|---|
| — | 10%+ Owner | 911,194 | — |
| — | 10%+ Owner | 827,888 | — |
| — | 10%+ Owner | 711,194 | — |
| — | 10%+ Owner | 343,764 | — |
| — | 10%+ Owner | 343,764 | — |
| — | 10%+ Owner | 281,419 | — |
| — | 10%+ Owner | 161,122 | — |
| — | 10%+ Owner | 101,255 | — |
| — | 10%+ Owner | 96,122 | — |
| — | CHIEF OPERATING OFFICER | 51,659 | — |
| — | CHIEF MEDICAL OFFICER | 38,563 | — |
| — | CHIEF SCIENTIFIC OFFICER | 24,732 | — |
| — | CHIEF SCIENTIFIC OFFICER | 14,172 | — |
| — | CHIEF FINANCIAL OFFICER | 5,666 | — |
| — | CHIEF DEVELOPMENT OFFICER | 4,916 | — |
| — | CHIEF OPERATING OFFICER | 3,705 | — |
| — | 10%+ Owner | 62 | — |
Form 4 reports a change in beneficial ownership by an officer, director or 10%+ holder, and must be filed within two business days of the transaction — so this is close to real time, unlike the 45-day-lagged 13F institutional data.
Transaction codes matter more than the raw buy/sell count. Code P is an open-market purchase — an insider choosing to buy with their own money, which is the signal most research treats as informative. Code S is a sale, but sales are frequently pre-scheduled under a 10b5-1 plan or cover tax withholding on vesting equity, so a run of sales often says nothing directional. Codes A and M are grants and option exercises rather than open-market decisions.
Full filing history and per-insider positions are on the GBIO quote page; the site-wide leaderboard is on the insider transactions hub.