SEC Insider Transactions from Cox John.

Last updated: 2026-03-14 11:56 UTC | Total transactions: 24

John Cox, CEO and President of Dyne Therapeutics ($DYN), made one open market purchase of shares in the last year totaling $911,000, with his most recent buy on July 14, 2025. This ranks 608th among nearly 5,000 insiders, below the average of 1.5 million per buyer and 3.3 transactions. He conducted four open market sales totaling $185,000, most recently on March 5, 2026, ranking 8,573rd out of about 12,000 sellers versus their 8.6 million average and 6.4 transactions.

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Transaction Date Company Ticker Insider Name Title Transaction Type Security Shares Price Shares Owned Following Total Shares Outstanding % of Owned % of Outstanding
March 5, 2026 Dyne Therapeutics, Inc. $DYN Cox John CEO & President S Common Stock 2732 $14.90 446,145.0000 142,824,687 0.61% 0.00%
Feb. 12, 2026 Dyne Therapeutics, Inc. $DYN Cox John CEO & President A Stock option (right to buy) 285000 $0.00 285,000.0000 142,824,687 9999.99% 0.20%
Feb. 12, 2026 Dyne Therapeutics, Inc. $DYN Cox John CEO & President A Common Stock 180000 $0.00 448,877.0000 142,824,687 66.95% 0.13%
Dec. 5, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President S Common Stock 2662 $20.72 268,877.0000 142,824,687 0.98% 0.00%
Sept. 5, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President S Common Stock 2640 $13.41 271,539.0000 113,121,357 0.96% 0.00%
July 16, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President A Stock option (right to buy) 197285 $0.00 197,285.0000 113,121,357 9999.99% 0.17%
July 15, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President G Common Stock 10000 $0.00 274,179.0000 113,121,357 3.52% 0.01%
July 14, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President P Common Stock 100000 $9.11 314,179.0000 113,121,357 46.69% 0.09%
July 15, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President G Common Stock 10000 $0.00 304,179.0000 113,121,357 3.18% 0.01%
July 15, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President G Common Stock 10000 $0.00 294,179.0000 113,121,357 3.29% 0.01%
July 15, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President G Common Stock 10000 $0.00 284,179.0000 113,121,357 3.40% 0.01%
June 5, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President S Common Stock 4060 $13.35 174,179.0000 113,121,357 2.28% 0.00%
March 5, 2025 Dyne Therapeutics, Inc. $DYN Cox John CEO & President S Common Stock 4061 $11.83 178,239.0000 113,121,357 2.23% 0.00%
Dec. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President A Stock option (right to buy) 232100 $0.00 232,100.0000 0 9999.99% 0.00%
Dec. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President A Common Stock 145300 $0.00 182,300.0000 0 392.70% 0.00%
Sept. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President P Common Stock 7200 $33.09 37,000.0000 0 24.16% 0.00%
Sept. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President P Common Stock 800 $32.57 29,800.0000 0 2.76% 0.00%
Sept. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President P Common Stock 7200 $33.09 37,000.0000 0 24.16% 0.00%
Sept. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President P Common Stock 7200 $33.09 37,000.0000 0 24.16% 0.00%
Sept. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President P Common Stock 800 $32.57 29,800.0000 0 2.76% 0.00%
Sept. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President P Common Stock 800 $32.57 29,800.0000 0 2.76% 0.00%
Sept. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President P Common Stock 7200 $33.09 37,000.0000 0 24.16% 0.00%
Sept. 4, 2024 Dyne Therapeutics, Inc. $DYN Cox John CEO & President P Common Stock 800 $32.57 29,800.0000 0 2.76% 0.00%
March 25, 2024 Dyne Therapeutics, Inc. $DYN Cox John See Remarks A Stock Option (Right to Buy) 679853 $0.00 679,853.0000 0 9999.99% 0.00%