John Cox 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 John reports to the SEC
Open-market buys and sales
29 trades reported on SEC Form 4, newest first
| Date | Stock | Type | Shares | Price | Value | Holding | Reported |
|---|---|---|---|---|---|---|---|
| Sep 8, 2026 | DYN | ↓ Sell | 5,658 | $18.88 | $107K | Direct | Sep 8, 2026 (0d) |
| Aug 13, 2026 | DYN | ↓ Sell | 4,986 | $26.28 | $131K | Direct | Aug 17, 2026 (4d) |
| Jun 16, 2026 | DYN | ↓ Sell | 2,683 | $18.33 | $49K | Direct | Jun 17, 2026 (1d) |
| May 13, 2026 | DYN | ↓ Sell | 3,311 | $18.36 | $61K | Direct | May 14, 2026 (1d) |
| Mar 5, 2026 | DYN | ↓ Sell | 2,732 | $14.90 | $41K | Direct | Mar 6, 2026 (1d) |
| Dec 5, 2025 | DYN | ↓ Sell | 2,662 | $20.72 | $55K | Direct | Dec 5, 2025 (0d) |
| Sep 5, 2025 | DYN | ↓ Sell | 2,640 | $13.41 | $35K | Direct | Sep 9, 2025 (4d) |
| Jul 14, 2025 | DYN | ↑ Buy | 100,000 | $9.11 | $911K | Direct | Jul 15, 2025 (1d) |
| Jun 5, 2025 | DYN | ↓ Sell | 4,060 | $13.35 | $54K | Direct | Jun 6, 2025 (1d) |
| Mar 5, 2025 | DYN | ↓ Sell | 4,061 | $11.83 | $48K | Direct | Mar 7, 2025 (2d) |
| Sep 4, 2024 | DYN | ↑ Buy | 8,000 | $33.04 | $264K | By Trust #2 | Sep 4, 2024 (0d) |
| Sep 4, 2024 | DYN | ↑ Buy | 8,000 | $33.04 | $264K | By Trust #1 | Sep 4, 2024 (0d) |
| Sep 4, 2024 | DYN | ↑ Buy | 8,000 | $33.04 | $264K | By Trust #3 | Sep 4, 2024 (0d) |
| Sep 4, 2024 | DYN | ↑ Buy | 8,000 | $33.04 | $264K | By Trust #4 | Sep 4, 2024 (0d) |
| Mar 24, 2020 | RGEN | ↓ Sell | 1,858 | $96.72 | $180K | Direct | Mar 26, 2020 (2d) |
| Mar 18, 2020 | RGEN | ↓ Sell | 26,736 | $95.27 | $2.5M | Direct | Mar 20, 2020 (2d) |
| Mar 4, 2020 | RGEN | ↓ Sell | 10,000 | $93.39 | $934K | Direct | Mar 5, 2020 (1d) |
| Feb 24, 2020 | RGEN | ↓ Sell | 4,455 | $92.81 | $413K | Direct | Feb 26, 2020 (2d) |
| Mar 25, 2015 | BIIB | ↓ Sell | 12,010 | $449.06 | $5.4M | Direct | Mar 26, 2015 (1d) |
| Nov 1, 2011 | BIIB | ↓ Sell | 2,175 | $114.37 | $249K | Direct | Nov 3, 2011 (2d) |
| Apr 21, 2011 | BIIB | ↓ Sell | 4,350 | $100.00 | $435K | Direct | Apr 25, 2011 (4d) |
| Apr 13, 2011 | BIIB | ↓ Sell | 36,234 | $80.00 | $2.9M | Direct | Apr 15, 2011 (2d) |
| Apr 11, 2011 | BIIB | ↓ Sell | 6,900 | $78.00 | $538K | Direct | Apr 13, 2011 (2d) |
| Mar 31, 2011 | BIIB | ↓ Sell | 2,840 | $73.00 | $207K | Direct | Apr 1, 2011 (1d) |
| Mar 2, 2011 | BIIB | ↓ Sell | 4,041 | $70.10 | $283K | Direct | Mar 3, 2011 (1d) |
| Feb 17, 2011 | BIIB | ↓ Sell | 1,843 | $67.08 | $124K | Direct | Feb 18, 2011 (1d) |
| Nov 9, 2010 | BIIB | ↓ Sell | 773 | $62.87 | $49K | Direct | Nov 10, 2010 (1d) |
| Nov 2, 2010 | BIIB | ↓ Sell | 765 | $63.04 | $48K | Direct | Nov 3, 2010 (1d) |
| Oct 28, 2010 | BIIB | ↓ Sell | 6,900 | $63.00 | $435K | Direct | Oct 29, 2010 (1d) |
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 John Cox's insider trades
John Cox is CEO & President at Dyne Therapeutics (DYN). Since Oct 28, 2010, John has reported 5 open-market purchases worth $2.0M and 24 sales worth $15.3M on SEC Form 4. In the last 12 months: 6 sales ($444K).
Their filings also include option exercises (24 filings), shares withheld for taxes (24 filings), grants and awards (23 filings), other transactions (5 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.