X0508 4 2025-11-12 0 0001178670 ALNYLAM PHARMACEUTICALS, INC. ALNY 0001446125 Greenstreet Yvonne 675 WEST KENDALL STREET HENRI A. TERMEER SQUARE CAMBRIDGE MA 02142 1 1 0 0 Chief Executive Officer 1 Common Stock 2025-11-12 4 M 0 650 42.22 A 66059 D Common Stock 2025-11-12 4 M 0 15000 119.13 A 81059 D Common Stock 2025-11-12 4 S 0 711 448.07 D 80348 D Common Stock 2025-11-12 4 S 0 2132 449.15 D 78216 D Common Stock 2025-11-12 4 S 0 453 450.17 D 77763 D Common Stock 2025-11-12 4 S 0 1255 451.16 D 76508 D Common Stock 2025-11-12 4 S 0 1210 452.43 D 75298 D Common Stock 2025-11-12 4 S 0 1069 453.52 D 74229 D Common Stock 2025-11-12 4 S 0 1960 454.84 D 72269 D Common Stock 2025-11-12 4 S 0 3406 455.56 D 68863 D Common Stock 2025-11-12 4 S 0 2420 456.64 D 66443 D Common Stock 2025-11-12 4 S 0 604 457.71 D 65839 D Common Stock 2025-11-12 4 S 0 430 458.42 D 65409 D Common Stock 2025-11-13 4 M 0 10000 119.13 A 75409 D Common Stock 2025-11-13 4 S 0 654 447.73 D 74755 D Common Stock 2025-11-13 4 S 0 1013 448.76 D 73742 D Common Stock 2025-11-13 4 S 0 1477 450.02 D 72265 D Common Stock 2025-11-13 4 S 0 2218 450.69 D 70047 D Common Stock 2025-11-13 4 S 0 1702 451.94 D 68345 D Common Stock 2025-11-13 4 S 0 1599 452.85 D 66746 D Common Stock 2025-11-13 4 S 0 881 453.99 D 65865 D Common Stock 2025-11-13 4 S 0 195 454.69 D 65670 D Common Stock 2025-11-13 4 S 0 261 456.03 D 65409 D Common Stock 407 I by Managed Account Performance Stock Option 2016 (right to buy) 42.22 2025-11-12 4 M 0 650 0.0 D 2019-08-06 2026-12-20 Common Stock 650 0 D Performance Stock Option 2017 (right to buy) 119.13 2025-11-12 4 M 0 15000 0.0 D 2021-02-11 2028-03-01 Common Stock 15000 10000 D Performance Stock Option 2017 (right to buy) 119.13 2025-11-13 4 M 0 10000 0.0 D 2021-02-11 2028-03-01 Common Stock 10000 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 August 13, 2025. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $447.67 to $448.67. 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 $448.69 to $449.69. 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 $449.72 to $450.64. 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 $450.75 to $451.55. 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 $451.95 to $452.89. 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 $453.14 to $454.11. 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 $454.16 to $455.16. 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 $455.17 to $456.15. 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 price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $456.22 to $457.19. 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 $457.24 to $458.06. 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 $458.37 to $458.56. 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 $447.30 to $448.24. 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 $448.38 to $449.31. 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 $449.50 to $450.50. 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 $450.56 to $451.50. 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 $451.60 to $452.31. 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 $452.51 to $453.50. 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 $453.55 to $454.46. 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. Reflects shares of ALNY common stock acquired by the Reporting Person under the issuer 401(k) plan as a result of the issuer 401(k) matching contribution program. This stock option was fully vested and exercisable as of August 6, 2019. This stock option was fully vested and exercisable as of February 11, 2021. By: Brett Budzinski, Attorney-in-Fact For: Yvonne Greenstreet 2025-11-14