Form 4 Filing for David E.I. Pyott

This filing details transactions made by David E.I. Pyott, a director at ALNYLAM PHARMACEUTICALS, INC. On May 20, 2026, Pyott acquired 671 shares of Common Stock, represented by restricted stock units (RSUs) granted under the company's stock incentive plan. These RSUs vest on the first anniversary of the grant date or upon earlier retirement/resignation under specific conditions. The acquired shares were purchased by the David E.I. Pyott Trust, of which Pyott is the trustee. Additionally, Pyott acquired a stock option (right to buy) for 1441 shares of Common Stock. This option will vest in full on the first anniversary of the grant date or upon earlier retirement/resignation, with vesting conditions similar to the RSUs. The option has an exercise price of $298.48 and an expiration date of May 20, 2036. Following these transactions, Pyott holds 27,900 shares of Common Stock indirectly through the trust and has 1,441 shares directly from the option grant.