Brian S Posner insider trades: Dyne Therapeutics (DYN) stock buys and sales
Trades on the price chart
Daily close, with an arrow on each day they bought or sold
Companies
Where Brian reports to the SEC
and 1 more company
Open-market buys and sales
40 trades reported on SEC Form 4, newest first
| Date | Stock | Type | Shares | Price | Value | Holding | Reported |
|---|---|---|---|---|---|---|---|
| Oct 2, 2026 | DYN | ↑ Buy | 2,500 | $16.00 | $40K | Direct | Oct 6, 2026 (4d) |
| Jun 8, 2026 | DYN | ↑ Buy | 2,000 | $16.94 | $34K | Direct | Jun 9, 2026 (1d) |
| May 26, 2026 | DYN | ↑ Buy | 2,000 | $18.21 | $36K | Direct | May 28, 2026 (2d) |
| May 20, 2026 | DYN | ↑ Buy | 2,500 | $17.12 | $43K | Direct | May 22, 2026 (2d) |
| May 11, 2026 | ACGL | ↓ Sell | 2,000 | $17.14 | $34K | Direct | May 12, 2026 (1d) |
| Mar 30, 2026 | DYN | ↑ Buy | 2,000 | $17.08 | $34K | Direct | Apr 1, 2026 (2d) |
| Mar 11, 2026 | ACGL | ↓ Sell | 3,000 | $17.11 | $51K | Direct | Mar 12, 2026 (1d) |
| Mar 6, 2026 | DYN | ↑ Buy | 3,000 | $15.06 | $45K | Direct | Mar 10, 2026 (4d) |
| Aug 1, 2025 | ACGL | ↑ Buy | 1,000 | $17.34 | $17K | Direct | Aug 4, 2025 (3d) |
| Oct 28, 2022 | ACGL | ↑ Buy | 2,000 | $17.60 | $35K | Direct | Nov 1, 2022 (4d) |
| Apr 29, 2022 | ACGL | ↑ Buy | 2,000 | $19.23 | $38K | Direct | May 2, 2022 (3d) |
| Jun 14, 2021 | ACGL | ↓ Sell | 4,000 | $25.24 | $101K | Direct | Jun 15, 2021 (1d) |
| Jun 4, 2021 | BIIB | ↓ Sell | 360 | $274.17 | $99K | Direct | Jun 7, 2021 (3d) |
| May 13, 2020 | ACGL | ↑ Buy | 1,000 | $22.16 | $22K | Direct | May 15, 2020 (2d) |
| May 6, 2020 | ACGL | ↑ Buy | 1,000 | $23.72 | $24K | Direct | May 8, 2020 (2d) |
| Dec 2, 2019 | BIIB | ↓ Sell | 1,055 | $292.35 | $308K | Direct | Dec 3, 2019 (1d) |
| Nov 28, 2018 | ACGL | ↑ Buy | 500 | $28.24 | $14K | Direct | Nov 29, 2018 (1d) |
| Nov 28, 2018 | ACGL | ↑ Buy | 500 | $21.86 | $11K | Direct | Nov 29, 2018 (1d) |
| Nov 5, 2018 | ACGL | ↑ Buy | 2,500 | $22.45 | $56K | Direct | Nov 6, 2018 (1d) |
| May 3, 2018 | ACGL | ↑ Buy | 3,000 | $78.63 | $236K | Direct | May 4, 2018 (1d) |
| Aug 9, 2017 | BIVV | ↑ Buy | 1,000 | $59.19 | $59K | Direct | Aug 10, 2017 (1d) |
| Jun 9, 2017 | BIIB | ↓ Sell | 1,084 | $256.31 | $278K | Direct | Jun 12, 2017 (3d) |
| May 24, 2017 | BIVV | ↑ Buy | 2,000 | $53.86 | $108K | Direct | May 24, 2017 (0d) |
| Nov 18, 2016 | ACGL | ↑ Buy | 6,000 | $21.88 | $131K | Direct | Nov 21, 2016 (3d) |
| Jun 22, 2015 | BIIB | ↓ Sell | 470 | $415.00 | $195K | Direct | Jun 23, 2015 (1d) |
| Jun 15, 2015 | BIIB | ↓ Sell | 400 | $386.64 | $155K | Direct | Jun 16, 2015 (1d) |
| Jun 20, 2014 | BIIB | ↓ Sell | 605 | $315.00 | $191K | Direct | Jun 23, 2014 (3d) |
| Jun 13, 2014 | BIIB | ↓ Sell | 700 | $310.50 | $217K | Direct | Jun 16, 2014 (3d) |
| Mar 31, 2014 | BIIB | ↓ Sell | 3,000 | $296.76 | $890K | Direct | Apr 1, 2014 (1d) |
| Aug 19, 2013 | ACGL | ↑ Buy | 2,500 | $23.58 | $59K | Direct | Aug 20, 2013 (1d) |
| Aug 2, 2013 | ACGL | ↑ Buy | 5,000 | $25.25 | $126K | Direct | Aug 5, 2013 (3d) |
| Jun 11, 2013 | BIIB | ↓ Sell | 2,020 | $219.62 | $444K | Direct | Jun 13, 2013 (2d) |
| Mar 18, 2013 | BIIB | ↓ Sell | 4,500 | $174.81 | $787K | Direct | Mar 19, 2013 (1d) |
| Nov 19, 2012 | BGMD | ↑ Buy | 10,000 | $1.17 | $12K | Direct | Nov 20, 2012 (1d) |
| Jun 7, 2012 | BIIB | ↓ Sell | 2,500 | $135.00 | $338K | Direct | Jun 11, 2012 (4d) |
| Jun 4, 2012 | BIIB | ↓ Sell | 2,400 | $126.45 | $303K | Direct | Jun 5, 2012 (1d) |
| May 22, 2012 | BGMD | ↑ Buy | 10,000 | $4.04 | $40K | Direct | May 23, 2012 (1d) |
| Aug 29, 2011 | BIIB | ↓ Sell | 15,000 | $92.53 | $1.4M | Direct | Aug 31, 2011 (2d) |
| May 25, 2011 | BIIB | ↓ Sell | 25,975 | $94.09 | $2.4M | Direct | May 27, 2011 (2d) |
| Oct 11, 2006 | SCD | ↑ Buy | 5,000 | $17.95 | $90K | Direct | Oct 11, 2006 (0d) |
Each row is one filing's trades in one stock, summed. Shares and prices are as filed, before any later stock split.
Other DYN insiders
Open-market trades in the last 12 months
About Brian S Posner's insider trades
Brian S Posner is an insider at Dyne Therapeutics (DYN). Since Oct 11, 2006, Brian has reported 23 open-market purchases worth $1.3M and 17 sales worth $8.2M on SEC Form 4. In the last 12 months: 6 buys ($232K) and 2 sales ($86K).
Their filings also include grants and awards (40 filings), shares returned to the company (5 filings), option exercises (4 filings), gifts (3 filings). These aren't open-market trades and aren't counted above.
How to read insider trades
Officers, directors and owners of more than 10% of a company must report trades in its stock on SEC Form 4, usually within two business days. Purchases with their own money are the stronger signal: insiders sell for many reasons (taxes, diversification, a house), but buy for one. See every DYN insider trade, the latest insider trades across the market, or cluster buys, when several insiders buy the same stock within days.