Posner Brian S
SEC insider (Form 3/4/5 filer). CIK 0001372455. Director at Dyne Therapeutics, Inc. (DYN) and 1 other issuer. 16 reported Form 4/5 transactions since Sep 2024; latest on Oct 2, 2026. Located in WALTHAM, MA.
Companies Posner Brian S has filed insider reports for
- Dyne Therapeutics, Inc. (DYN): Director
- ARCH CAPITAL GROUP LTD. (ACGL): Director
Posner Brian S
CIK: 0001372455
Transaction Breakdown
High conviction signal
Position reduction
Derivative conversions
Compensation grants
Gifts, tax withholding, conversions, dispositions to the issuer and other codes
Discretionary Trading P&L
Holdings
Transaction History (16 total)
- Oct 2, 2026DYN
Dyne Therapeutics, Inc.
PurchaseDirect2.5K shares at avg. $16.00$40K - Jun 8, 2026DYN
Dyne Therapeutics, Inc.
PurchaseDirect2K shares at avg. $16.94$34K - Jun 5, 2026DYN
Dyne Therapeutics, Inc.
AwardDirectStock option (right to buy)
35.2K shares- - Jun 3, 2026DYN
Dyne Therapeutics, Inc.
PurchaseDirect2.5K shares at avg. $17.48$44K - Jun 3, 2026ACGL
ARCH CAPITAL GROUP LTD.
SaleDirect3K shares at avg. $19.66$59K - May 26, 2026DYN
Dyne Therapeutics, Inc.
PurchaseDirect2K shares at avg. $18.21$36K - May 20, 2026DYN
Dyne Therapeutics, Inc.
PurchaseDirect2.5K shares at avg. $17.12$43K - May 11, 2026ACGL
ARCH CAPITAL GROUP LTD.
SaleDirect2K shares at avg. $17.14$34K - May 5, 2026ACGL
ARCH CAPITAL GROUP LTD.
AwardDirect2.1K shares- - Mar 30, 2026DYN
Dyne Therapeutics, Inc.
PurchaseDirect2K shares at avg. $17.08$34K
| Type | Shares | Price | Ownership | |||
|---|---|---|---|---|---|---|
| Oct 2, 2026 |  DYN Dyne Therapeutics, Inc. | Purchase | 2,500 | $16.00 | $40,000 | Direct |
| Jun 8, 2026 | DYN Dyne Therapeutics, Inc. | Purchase | 2,000 | $16.94 | $33,880 | Direct |
| Jun 5, 2026 | DYN Dyne Therapeutics, Inc. | Award Stock option (right to buy) | 35,152 | - | - | Direct |
| Jun 3, 2026 | DYN Dyne Therapeutics, Inc. | Purchase | 2,500 | $17.48 | $43,700 | Direct |
| Jun 3, 2026 |  ACGL ARCH CAPITAL GROUP LTD. | Sale | 3,000 | $19.66 | $58,980 | Direct |
| May 26, 2026 | DYN Dyne Therapeutics, Inc. | Purchase | 2,000 | $18.21 | $36,420 | Direct |
| May 20, 2026 | DYN Dyne Therapeutics, Inc. | Purchase | 2,500 | $17.12 | $42,800 | Direct |
| May 11, 2026 | ACGL ARCH CAPITAL GROUP LTD. | Sale | 2,000 | $17.14 | $34,283 | Direct |
| May 5, 2026 | ACGL ARCH CAPITAL GROUP LTD. | Award | 2,071 | - | $0 | Direct |
| Mar 30, 2026 | DYN Dyne Therapeutics, Inc. | Purchase | 2,000 | $17.08 | $34,160 | Direct |
1-10 of 16 transactions