The 2025 Annual Meeting of Stockholders will be held on May 8, 2025 at 8:30 a.m. ET and will be a completely virtual meeting. There will be no physical meeting location. The meeting will only be conducted via live webcast. To participate in the virtual meeting, visit www.virtualshareholdermeeting.com/ALNY2025 and enter the 16-digit control number included on your proxy card or on the instructions that accompanied your proxy materials. You may begin to log into the meeting platform beginning at 8:15 a.m. ET on May 8, 2025.

If you wish to submit a question, you may do so in two ways. If you want to ask a question before the meeting, then beginning on March 24, 2025 and until 11:59 p.m. on May 7, 2025, you may log into www.proxyvote.com and enter your 16-digit control number. Once past the login screen, click on “Questions for Management,” type in your question, and click “Submit.” Alternatively, if you want to submit your question during the meeting, log into the virtual meeting platform at www.virtualshareholdermeeting.com/ALNY2025, type your question into the “Ask a Question” field, and click “Submit.” Questions pertinent to meeting matters will be answered during the meeting, subject to time constraints. Any questions pertinent to meeting matters that cannot be answered during the meeting due to time constraints will be posted online and answered at http://investors.alnylam.com/shareholder-services/annual-meeting. The questions and answers will be available as soon as practical after the meeting and will remain available until one week after posting.

If you encounter any technical difficulties with the virtual meeting platform on the meeting day, please call 1-855-449-0991 (Toll Free) or 1-720-378-5962 (International Toll). Technical support will be available starting at 8:00 a.m. ET on May 8, 2025 and will remain available until thirty minutes after the meeting has finished.