X0609 4 2026-06-01 0001178670 ALNYLAM PHARMACEUTICALS, INC. ALNY 0001051578 PYOTT DAVID E I false 675 WEST KENDALL STREET CAMBRIDGE MA 02142 1 1 Common Stock 2026-06-01 4 M 0 3830 0 A 5412 D Common Stock 2026-06-01 4 S 0 921 297.71 D 4491 D Common Stock 2026-06-01 4 S 0 1175 298.91 D 3316 D Common Stock 2026-06-01 4 S 0 1222 299.87 D 2094 D Common Stock 2026-06-01 4 S 0 495 300.72 D 1599 D Common Stock 2026-06-01 4 S 0 17 302.65 D 1582 D Common Stock 27900 I by Trust Stock Option (Right to Buy) 70.20 2026-06-01 4 M 0 3830 0 D 2017-06-03 2026-06-03 Common Stock 3830 0 D The transactions reported on this Form 4 were made pursuant to a Rule 10b5-1(c) trading plan adopted by the reporting person on November 12, 2025. The options exercised by the reporting person were due to expire on June 3, 2026. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $297.31 to $297.99. The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $298.33 to $299.33. The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $299.36 to $300.19. The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $300.45 to $301.15. The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range. The shares of ALNY common stock were purchased by the David E I Pyott Trust, of which the reporting person is trustee. This stock option was fully vested and exercisable as of June 3, 2017. Brett Budzinski, Attorney-in-Fact For: David E.I. Pyott 2026-06-03