X0306 4 2020-09-09 0 0001178670 ALNYLAM PHARMACEUTICALS, INC. ALNY 0001291963 Greene Barry E 675 WEST KENDALL STREET HENRI A. TERMEER SQUARE CAMBRIDGE MA 02142 0 1 0 0 President Common Stock 2020-07-16 5 G 0 3176 0.0 A 65412 D Common Stock 2020-09-09 4 M 0 44530 9.14 A 114873 D Common Stock 2020-09-09 4 S 0 14075 122.66 D 100798 D Common Stock 2020-09-09 4 S 0 27109 123.39 D 73689 D Common Stock 2020-09-09 4 S 0 3346 124.38 D 70343 D Common Stock 2020-07-16 5 G 0 155 0.0 A 155 I by Dependent Common Stock 2020-07-16 5 G 0 155 0.0 D 3331 I by Trust Common Stock 2020-07-16 5 G 0 155 0.0 D 3176 I by Trust Common Stock 2020-07-16 5 G 0 3176 0.0 D 0 I by Trust Common Stock 3003 I by Managed Account Stock Option (right to buy) 9.14 2020-09-09 4 M 0 44530 0.0 D 2020-12-08 Common Stock 44530 0 D Represents shares of ALNY common stock distributed upon termination of the Barry E. Greene Qualified Annuity Interest Trust (GRAT), of which the reporting person is the sole Trustee. Upon termination of the trust on July 16, 2020, 155 of the shares held by the GRAT were gifted to a non-dependent child, and 155 of the shares were transferred to the reporting persons dependent child. The remaining 3,176 shares were distributed to the reporting person. All sales reported on this Form 4 were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on February 13, 2020. The 44,530 options exercised and sold by the reporting person were due to expire on December 8, 2020. Sale prices ranged from $122.00 to $123.00. Sale prices ranged from $123.01 to $124.00. Sale prices ranged from $124.03 to $124.87. Reflects shares of ALNY common stock acquired by the reporting person under the ALNY 401(k) plan as a result of the ALNY 401(k) matching contribution program. The stock option vested as to 25% of the shares on the 1st anniversary of the date of the stock option grant and as to an additional 6.25% of the shares each successive three month period thereafter. By: /s/ Mary Beth DeLena, Attorney-in-Fact For: Barry E. Greene 2020-09-11