Person

Brian S. Posner

Director, Arch Capital Group

Current S&P 500 boards
1
Current roles
1
Open-market buys
$585K
Open-market sales
$931K

Current roles

From Section 16 filings (Forms 3, 4 and 5) in the last 13 months.

Past roles

“Last filing” is the latest Form 3/4/5 for that company, an upper bound on the end date.

  • BIIB
    Biogen
    Director
    Jun 2016 – last filing Jan 2023

Sits alongside

People who currently share a board or management team with this person.

Open-market trades

Purchases and sales reported on Form 4 at S&P 500 companies.

DateCompanyTypeSharesPriceValue
Jun 3, 2026ACGLSale3,000$19.66$59K
May 11, 2026ACGLSale2,000$17.14$34K
Mar 11, 2026ACGLSale3,000$17.12$51K
Aug 1, 2025ACGLBuy1,000$17.34$17K
Oct 28, 2022ACGLBuy2,000$17.60$35K
Apr 29, 2022ACGLBuy2,000$19.23$38K
Jun 14, 2021ACGLSale4,000$25.24$101K
Jun 4, 2021BIIBSale360$274.17$99K
May 13, 2020ACGLBuy1,000$22.16$22K
May 6, 2020ACGLBuy1,000$23.72$24K
Dec 2, 2019BIIBSale1,055$292.35$308K
Nov 28, 2018ACGLBuy500$21.86$11K
Nov 28, 2018ACGLBuy500$28.24$14K
Nov 5, 2018ACGLBuy2,500$22.45$56K
May 3, 2018ACGLBuy1,000$77.38$77K
May 3, 2018ACGLBuy2,000$79.25$159K
Jun 9, 2017BIIBSale1,084$256.31$278K
Nov 18, 2016ACGLBuy6,000$21.88$131K

SEC reporting-owner ID (CIK) 1372455 · all filings on EDGAR