X0508 4 2025-12-18 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 2025-12-18 4 M 0 4440 17.16 A 308351 D Common Stock 2025-12-18 4 M 0 6259 30.46 A 314610 D Common Stock 2025-12-18 4 S 0 350 162.26 D 314260 D Common Stock 2025-12-18 4 S 0 1465 163.19 D 312795 D Common Stock 2025-12-18 4 S 0 447 164.24 D 312348 D Common Stock 2025-12-18 4 S 0 697 165.21 D 311651 D Common Stock 2025-12-18 4 S 0 1783 166.60 D 309868 D Common Stock 2025-12-18 4 S 0 1431 167.29 D 308437 D Common Stock 2025-12-18 4 S 0 2175 168.54 D 306262 D Common Stock 2025-12-18 4 S 0 1938 169.58 D 304324 D Common Stock 2025-12-18 4 S 0 362 170.26 D 303962 D Common Stock 2025-12-18 4 S 0 51 171.20 D 303911 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) 17.16 2025-12-18 4 M 0 4440 0 D 2027-05-17 Common Stock 4440 62160 D Stock Option (right to buy) 30.46 2025-12-18 4 M 0 6259 0 D 2028-01-04 Common Stock 6259 87627 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 350 shares sold at prices ranging from $161.72 to $162.69 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 1,465 shares sold at prices ranging from $162.72 to $163.62 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 447 shares sold at prices ranging from $163.75 to $164.73 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 697 shares sold at prices ranging from $164.83 to $165.67 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 1,783 shares sold at prices ranging from $166.00 to $166.99 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 1,431 shares sold at prices ranging from $167.00 to $167.95 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 2,175 shares sold at prices ranging from $168.01 to $169.00 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 1,938 shares sold at prices ranging from $169.01 to $170.00 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 362 shares sold at prices ranging from $170.02 to $170.91 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 51 shares sold at prices ranging from $171.09 to $171.35 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. All options are currently exercisable. /s/ William Lewis, by Michael A. Smith as Attorney-in-fact 2025-12-19