Brian S Posner
CIK 1372455 · last filed 2026-10-06
"Disclosed insider exposure" sums this person's most-recently-reported share counts across each company they're an insider in, multiplied by the current underlying price. It is not net worth — it misses retail holdings, private investments, real estate, index funds, and any company where the person isn't an SEC-reporting insider. For informational purposes only.
Charts
Trading activity, where the exposure sits, and each trade against the stock price.
BIIB price and trades
Daily close with each Form 4 filing on this company marked: green = open-market buy, red = open-market sale, purple = grants, exercises, gifts and other non-market transactions. Marker size scales with the dollar value.
Shares held
Shares owned after each reported transaction on this company (direct holdings as reported).
Open-market buying and selling
by monthDollar value of open-market purchases (code P, up) and sales (code S, down) across all companies, by filing month. Grants, exercises and gifts are excluded.
Exposure by company
latestMost recently reported shares × current price. Faded bars (*) have had no filing in 3 years, so the person may no longer hold them. Click a bar to chart that company.
Filer Profile
CAMBRIDGE, MA 02142
Holdings By Company
| Symbol | Role | Shares | Price | Disclosed Exposure | Lifetime OM Net | Filings | Latest Filed |
|---|---|---|---|---|---|---|---|
| DYN | Director | 27,000 | $16.64 | $449.4K | $314.8K | 9 | 2026-10-06 |
| ACGLO | Director | 0 | $18.02 | $0 | $208.3K | 21 | 2026-06-04 |
| BIIB | Director | 8,175 | $251.44 | $2.06M | -$6.74M | 26 | 2021-07-02 |
| Bioverativ Inc. (BIVV) Delisted | Director | 0 | — | — | $166.9K | 7 | 2018-03-08 |
| ACGL | Director | 18,000 | $100.63 | $1.81M | $316.4K | 13 | 2018-01-02 |
| BG Medicine, Inc. (BGMD) Delisted | Director | 5,000 | — | — | $52.0K | 4 | 2013-06-14 |
| ANADYS PHARMACEUTICALS INC (ANDS) Delisted | Director | — | — | — | $0 | 1 | 2011-08-24 |
Recent Filings · Page 5 of 9
81 filings| Filed | Symbol | Action | Net Shares | Net $ | Link |
|---|---|---|---|---|---|
| 2017-09-26 | ACGL | Disp (D) | −695 | -$17.4K | EDGAR |
| 2017-09-19 | ACGL | Disp (D) | −4,659 | -$116.5K | EDGAR |
| 2017-08-10 | Bioverativ Inc. (BIVV) Delisted | Buy (P) | +1,000 | $59.2K | EDGAR |
| 2017-06-12 | BIIB | Sell (S) | −1,084 | -$277.8K | EDGAR |
| 2017-06-09 | BIIB | Grant (A) | +1,055 | $0 | EDGAR |
| 2017-05-24 | Bioverativ Inc. (BIVV) Delisted | Buy (P) | +2,000 | $107.7K | EDGAR |
| 2017-05-05 | ACGL | Grant (A) | +2,057 | $0 | EDGAR |
| 2017-04-17 | Bioverativ Inc. (BIVV) Delisted | Grant (A) | +1,056 | $60.0K | EDGAR |
| 2017-03-27 | Bioverativ Inc. (BIVV) Delisted | Grant (A) | — | $0 | EDGAR |
| 2017-02-16 | Bioverativ Inc. (BIVV) Delisted | Grant (A) | — | $0 | EDGAR |
Notice (144 / 144/A): Form 144 is a notice of intent to sell restricted/control stock under Rule 144, filed before the sale; 144/A is an amendment. Many notices are pre-scheduled under Rule 10b5-1 plans. A Form 4 with code S typically follows within a few days when the planned sale executes; missing follow-up Form 4s suggest the notice was cancelled or modified.