Time on boards
- Boards served
- 3
- Current seats
- 3
- Board service
- 8 years
- Director since
- 2023
8 years of board service in total across 3 boards, counting each seat separately. Longest: Biogen Inc., 3 years.
Shareholder support
Support is votes for as a share of votes for and against (or withheld). Below 80% is a clear protest.
-
Dyne Therapeutics Inc. June 5, 202699.6%
-
Arch Capital Group Ltd. May 5, 2026100.0%
-
Arch Capital Group Ltd. May 4, 2023100.0%
Insider trades
All notable trades →From SEC Forms 4 and 5. Open-market purchases and sales are highlighted; grants, option exercises and shares withheld for tax are routine.
| Date | Company | Transaction | Shares | Price | Value |
|---|---|---|---|---|---|
| Oct 2, 2026 | Dyne Therapeutics Inc. | Open-market purchase | +2,500 | $16.00 | $40,000 |
| Jun 8, 2026 | Dyne Therapeutics Inc. | Open-market purchase | +2,000 | $16.94 | $33,880 |
| Jun 3, 2026 | Dyne Therapeutics Inc. | Open-market purchase | +2,500 | $17.48 | $43,700 |
| Jun 3, 2026 | Arch Capital Group Ltd. | Open-market sale | −3,000 | $19.66 | $58,980 |
| May 26, 2026 | Dyne Therapeutics Inc. | Open-market purchase | +2,000 | $18.21 | $36,420 |
| May 20, 2026 | Dyne Therapeutics Inc. | Open-market purchase | +2,500 | $17.12 | $42,800 |
| May 11, 2026 | Arch Capital Group Ltd. | Open-market sale | −2,000 | $17.14 | $34,280 |
| May 5, 2026 | Arch Capital Group Ltd. | Grant or award | +2,071 | — | — |
| Mar 30, 2026 | Dyne Therapeutics Inc. | Open-market purchase | +2,000 | $17.08 | $34,160 |
| Mar 11, 2026 | Dyne Therapeutics Inc. | Open-market purchase | +2,000 | $19.35 | $38,700 |
| Mar 11, 2026 | Arch Capital Group Ltd. | Open-market sale | −3,000 | $17.12 | $51,360 |
| Mar 6, 2026 | Dyne Therapeutics Inc. | Open-market purchase | +3,000 | $15.06 | $45,180 |
| Aug 1, 2025 | Arch Capital Group Ltd. | Open-market purchase | +1,000 | $17.34 | $17,340 |
| May 7, 2025 | Arch Capital Group Ltd. | Grant or award | +1,564 | — | — |
| May 9, 2024 | Arch Capital Group Ltd. | Grant or award | +1,455 | — | — |
Questions about Brian S. Posner
What boards is Brian S. Posner on?
Brian S. Posner sits on the boards of Arch Capital Group Ltd., Biogen Inc. and Dyne Therapeutics Inc.
How long has Brian S. Posner served on boards?
Our records show at least 8 years of board service across 3 boards, the earliest from 2023.
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