ALNYLAM PHARMACEUTICALS INC

Adoption of 10b5-1 Trading Plans by Our Officers and Directors

During our fiscal quarter ended March 31, 2024, certain of our officers (as defined in Rule 16a-1(f) under the Exchange Act) and directors entered into contracts, instructions or written plans for the purchase or sale of our securities that are intended to satisfy the conditions specified in Rule 10b5-1(c) under the Exchange Act for an affirmative defense against liability for trading in securities on the basis of material nonpublic information. We refer to these contracts, instructions, and written plans as “Rule 10b5-1 trading plans” and each one as a “Rule 10b5-1 trading plan.” We describe the material terms of these Rule 10b5-1 trading plans below.

Yvonne L. Greenstreet, MBChB, MBA, Chief Executive Officer and Director

On March 12, 2024, Yvonne L. Greenstreet, MBChB, MBA, our Chief Executive Officer, entered into a Rule 10b5-1 trading plan that provides that Dr. Greenstreet, acting through a broker, may sell up to an aggregate of 37,241 shares of our common stock received upon the settlement of awards granted to Dr. Greenstreet as equity incentive compensation, subject to adjustments for stock splits, stock combinations, stock dividends and other similar changes to our common stock. Sales of shares under the plan may only occur if the market price of our common stock is above specified prices from June 19, 2024 to March 7, 2025. The plan is scheduled to terminate on March 7, 2025, subject to earlier termination upon the sale of all shares subject to the plan, upon termination by Dr. Greenstreet or the broker, or as otherwise provided in the plan.

Amy W. Schulman, Director

On February 28, 2024, Amy W. Schulman, Chair of our board of directors, entered into a Rule 10b5-1 trading plan that provides that Ms. Schulman, acting through a broker, may sell up to an aggregate of 30,200 shares of our common stock received upon the exercise of options granted to Ms. Schulman as director compensation, subject to adjustments for stock splits, stock combinations, stock dividends and other similar changes to our common stock. Sales of shares under the plan may only occur if the market price of our common stock is above specified prices from May 29, 2024 to November 15, 2024. The plan is scheduled to terminate on November 15, 2024, subject to earlier termination upon the sale of all shares subject to the plan upon termination by Ms. Schulman or the broker, or as otherwise provided in the plan.