Alnylam Director Stuart Arbuckle Receives Equity Awards

This Form 4 filing reports that Stuart A. Arbuckle, a director of Alnylam Pharmaceuticals, received equity awards on May 20, 2026. The awards include 671 restricted stock units (RSUs) representing common stock and 1,441 stock options with an exercise price of $298.48 per share. Both awards have accelerated vesting provisions that allow for full vesting upon the earlier of the first anniversary of the grant date or the date of any earlier retirement or resignation, provided such retirement or resignation occurs no more than 90 days prior to the first anniversary. The RSUs and stock options were granted at $0 cost to the director. Following these transactions, Arbuckle holds 671 RSUs and 1,441 stock options. The filing was signed by Brett Budzinski as attorney-in-fact for Stuart A. Arbuckle on May 22, 2026.