Brian S. Posner

Companies

• Dyne Therapeutics, Inc.Board member Oct 2, 2025 to now¹
• Arch Capital GroupBoard member Nov 8, 2010 to now²
• BiogenBoard member Jul 24, 2008 to Jan 27, 2023³
• LMP CAPITAL & INCOME FUND INC.Officer of the Adviser Oct 11, 2006 to Oct 11, 2006⁴

Holdings

Stock this person has reported owning, from the forms officers and directors file with the SEC. See the biggest insider stakes.

Shares held

• Biogen BIIB8,025 shares⁵$1.9M at $241.24Jun 7, 2022
• DTDyne Therapeutics, Inc. DYN24,500 shares⁶$367.3K at $14.99Jun 8, 2026
• Arch Capital Group ACGL0 shares⁷Jun 3, 2026

As of each latest filing. The line shows shares held over time.

Recent filings

• Jun 8, 2026Bought 2,000 shares at $16.94 of Dyne Therapeutics, Inc.⁶
• Jun 3, 2026Sold 3,000 shares at $19.66 of Arch Capital Group⁷
• Jun 3, 2026Bought 2,500 shares at $17.48 of Dyne Therapeutics, Inc.⁸
• May 26, 2026Bought 2,000 shares at $18.21 of Dyne Therapeutics, Inc.⁹
• May 20, 2026Bought 2,500 shares at $17.12 of Dyne Therapeutics, Inc.¹⁰
• May 11, 2026Sold 2,000 shares at $17.14 of Arch Capital Group¹¹
• May 5, 2026Granted 2,071 shares of Arch Capital Group¹²
• Mar 30, 2026Bought 2,000 shares at $17.08 of Dyne Therapeutics, Inc.¹³
• Mar 11, 2026Sold 3,000 shares at $17.12 of Arch Capital Group¹⁴
• Mar 11, 2026Bought 2,000 shares at $19.35 of Dyne Therapeutics, Inc.¹⁵
• Mar 6, 2026Bought 3,000 shares at $15.06 of Dyne Therapeutics, Inc.¹⁶
• Aug 1, 2025Bought 1,000 shares at $17.34 of Arch Capital Group¹⁷
• May 7, 2025Granted 1,564 shares of Arch Capital Group¹⁸
• May 9, 2024Granted 1,455 shares of Arch Capital Group¹⁹
• May 4, 2023Granted 1,714 shares of Arch Capital Group²⁰
• Oct 28, 2022Bought 2,000 shares at $17.60 of Arch Capital Group²¹
• Jun 7, 2022Gift 150 shares of Biogen⁵
• May 4, 2022Granted 2,642 shares of Arch Capital Group²²
• May 4, 2022Granted 2,642 shares of Arch Capital Group²²
• Apr 29, 2022Bought 2,000 shares at $19.23 of Arch Capital Group²³
• Sep 30, 2021Returned to company 2,000 shares at $25.00 of Arch Capital Group²⁴