Transaction Details

Footnotes

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.