Transaction Details

Footnotes

Represents shares automatically sold by the Company on behalf of the reporting person pursuant to a mandatory sell-to-cover provision in the award agreement to cover minimum statutory tax withholding obligations upon the vesting of restricted stock units. | The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $318.27 to $319.27. 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 $319.28 to $320.28. 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 $320.33 to $321.33. 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 $321.34 to $322.31. 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 $322.36 to $323.36. 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 $323.38 to $324.35. 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 $324.39 to $325.38. 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 $325.40 to $326.21. 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.