X0609 4 2026-05-20 0001178670 ALNYLAM PHARMACEUTICALS, INC. ALNY 0001051578 PYOTT DAVID E I false 675 WEST KENDALL STREET CAMBRIDGE MA 02142 1 0 Common Stock 2026-05-20 4 A 0 671 0 A 1582 D Common Stock 27900 I by Trust Stock Option (Right to Buy) 298.48 2026-05-20 4 A 0 1441 0 A 2027-05-20 2036-05-20 Common Stock 1441 1441 D These shares are represented by restricted stock units (RSUs) granted under the Second Amended and Restated 2018 Stock Incentive Plan. Each RSU represents a contingent right to receive one share of common stock. The RSUs will vest in full upon the earlier of the first anniversary of the grant date and the date of any earlier retirement or resignation of the Reporting Person, provided such date of retirement or resignation occurs no more than 90 days prior to the first anniversary of the grant date. The shares of ALNY common stock were purchased by the David E I Pyott Trust, of which the reporting person is trustee. The stock option will vest in full upon the earlier of the first anniversary of the grant date and the date of any earlier retirement or resignation of the Reporting Person, provided such date of retirement or resignation occurs no more than 90 days prior to the first anniversary of the grant date. Brett Budzinski, Attorney-in-Fact For: David E.I. Pyott 2026-05-22