X0508 4 2026-02-19 0 0001104506 INSMED Inc INSM 0001402051 Lewis William 700 US HIGHWAY 202/206 BRIDGEWATER NJ 08807 1 1 0 0 Chair and CEO 1 Common Stock 2026-02-19 4 M 0 6259 30.46 A 307444 D Common Stock 2026-02-19 4 M 0 4440 17.16 A 311884 D Common Stock 2026-02-19 4 S 0 1988 149.17 D 309896 D Common Stock 2026-02-19 4 S 0 1891 150.10 D 308005 D Common Stock 2026-02-19 4 S 0 3413 151.12 D 304592 D Common Stock 2026-02-19 4 S 0 2377 151.92 D 302215 D Common Stock 2026-02-19 4 S 0 1030 153.38 D 301185 D Common Stock 233924 I By the Katie Procter Dynasty Trust Common Stock 50500 I By the William Lewis Family Legacy Trust Stock Option (right to buy) 30.46 2026-02-19 4 M 0 6259 0 D 2028-01-04 Common Stock 6259 62591 D Stock Option (right to buy) 17.16 2026-02-19 4 M 0 4440 0 D 2027-05-17 Common Stock 4440 44400 D This transaction was effected pursuant to a 10b5-1 trading plan adopted by the Reporting Person on September 4, 2025 in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended. This is the weighted average sales price representing 1,988 shares sold at prices ranging from $148.51 to $149.50 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request. This is the weighted average sales price representing 1,891 shares sold at prices ranging from $149.53 to $150.50 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request. This is the weighted average sales price representing 3,413 shares sold at prices ranging from $150.54 to $151.51 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request. This is the weighted average sales price representing 2,377 shares sold at prices ranging from $151.56 to $152.43 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request. This is the weighted average sales price representing 1,030 shares sold at prices ranging from $153.00 to $153.78 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request. The options became exercisable based on the following vesting schedule: 25% vested on the first anniversary of the grant date and an additional 12.5% vested on each sixth month anniversary date thereafter through the fourth anniversary of the date of grant. /s/ William Lewis, by Michael A. Smith as Attorney-in-fact 2026-02-23