Transaction Details

Footnotes

On March 1, 2024, the reporting person was granted a performance-based stock unit (PSU) under the 2018 Stock Incentive Plan. The shares subject to the PSU vest based on the achievement of three specified performance measures. The shares reported were issued to the reporting person upon vesting of forty (40) percent of the shares subject to the PSU based on the issuer publicly reporting $2.5 billion in annual net product revenue in accordance with GAAP, as determined by the People, Culture and Compensation Committee of the Issuer Board of Directors on January 11, 2026. | 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. | The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $353.53 to $354.41. 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 $354.54 to $355.53. 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 $356.62 to $356.61. 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 $356.63 to $357.63. 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 $357.68 to $358.68. 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 $358.69 to $359.66. 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 $359.79 to $360.79. 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 $360.90 to $361.89. 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 $361.93 to $362.92. 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 $362.99 to $363.99. 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 $364.00 to $365.00. 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 $365.01 to $366.01. 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 $366.03 to $366.96. 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 $367.04 to $368.00. 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 $368.09 to $369.08. 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 $369.13 to $369.93. 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 $370.43 to $371.23. 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 $372.35 to $372.50. 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 $374.08 to $374.89. 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. | This transaction was made pursuant to a Rule 10b5-1 (c) trading plan adopted by the Reporting Person on August 14, 2025. | The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $367.18 to $367.96. 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 $368.25 to $369.23. 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 $369.36 to $370.35. 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 $370.52 to $371.47. 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 $372.70 to $373.11. 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 $374.28 to $374.66. 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.