X0306 4 2020-02-26 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 Stock Option (right to buy) 118.05 2020-02-26 4 A 0 29925 0.0 A 2030-02-25 Common Stock 29925 29925 D Represents the time-vested stock option portion of the reporting person's Annual Equity Award for 2019. The reporting person also received 16,519 performance stock units that will vest upon the achievement of three specific performance conditions, which will be reported on a Form 4 if and when each performance condition is met and the performance stock units vest. The stock option vests 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 2020-02-28