Alnylam Pharmaceuticals 401(k) Plan
Officially: ALNYLAM PHARMACEUTICALS, INC. SAVINGS & INVESTMENT PLAN
The Alnylam Pharmaceuticals, Inc. Savings & Investment Plan is a 401(k) plan covering 1,815 active participants with total plan assets of $343.99 million as of December 31, 2024. Fidelity Investments Institutional serves as recordkeeper. The plan provides a discretionary matching contribution formula and includes auto-enrollment for newly eligible employees at a 6% default deferral rate.
By Zac Murphy, CFA charterholder and CFP professional. Published June 12, 2026. Verified against Form 5500 plan year 2024.
Get a personalized look at your Alnylam Pharmaceuticals 401(k) options
Not sure if you're getting the most out of your plan? Tell us a bit about your situation and we'll help you understand your options.
Fund lineup
Why our allocations use only index funds
The actively managed funds in this plan cost more per year than the plan's index funds, which run roughly 0.02% to 0.06%. Decades of research on long-term active fund performance do not support reliable outperformance net of fees, which is why the allocation ideas below may consider using only the low-cost index options.
Employer match
Estimates assume a constant salary and the match formula shown above. Your actual match depends on your plan's exact terms.
The cost of contributing only --%
On a $60,000 salary, contributing just half the match threshold would leave about -- in employer match unclaimed each year. Invested over 20 years at a hypothetical 7% annual return, that forgone match could have grown to roughly -- (a hypothetical illustration, not a projection). The match is the highest-return contribution you will make all year.
Sources
- Plan metadata (employer, participants, assets, plan year): Form 5500 annual return/report, plan year 2024 -- view filing
- Summary Plan Description (SPD) and fee disclosure (404a-5), where available from the plan administrator.
This page is for educational purposes only and does not constitute investment, tax, or legal advice, nor a recommendation to buy or sell any security. Information is drawn from public Form 5500 filings and plan documents and may be incomplete or out of date. You may consider consulting a qualified professional and confirming all details with your plan administrator before making decisions. Waterfall Planning is not affiliated with Alnylam Pharmaceuticals.
Find your risk profile
Answer 13 questions to see which allocation fits your situation.
Risk assessment methodology based on Grable, J. E., & Lytton, R. H. (1999). Financial risk tolerance revisited: The development of a risk assessment instrument. Financial Services Review, 8, 163-181.
Allocation ideas
Five sample mixes built from this plan's funds, from conservative to growth. Take the assessment above to see which one fits your risk profile.
Capital preservation with minimal market exposure, built from bonds and stable value.
Mostly bonds with a small stock sleeve for modest growth.
A classic 60/40 split of stocks and bonds.
Stock-heavy with a bond cushion for a long horizon.
All stocks for maximum long-term growth potential, with higher short-term volatility.
These allocation ideas are educational illustrations built from this plan's available funds and a standard risk-tolerance assessment. They are not personalized investment advice or a recommendation, and risk tolerance is only one factor in an investment decision. You may consider consulting a qualified professional before making changes to your account.