Alnylam is a commercial-stage biopharmaceutical company that pioneered RNA interference (RNAi) therapeutics — drugs that silence specific genes before they produce disease-causing proteins. Rather than blocking a protein after it is made, Alnylam's medicines use siRNA molecules to destroy the messenger RNA encoding a target protein, preventing its production entirely. Alnylam has six approved medicines, all based on this platform. The most important is AMVUTTRA (vutrisiran), which treats ATTR amyloidosis — a progressive disease in which misfolded transthyretin protein accumulates in the heart, nerves, and other tissues. AMVUTTRA is administered by subcutaneous injection once every three months and was approved for ATTR cardiomyopathy by the FDA in March 2025, opening a substantially larger addressable market beyond its original polyneuropathy indication. Alnylam's other directly-sold products — GIVLAARI and OXLUMO — treat ultra-rare genetic diseases with small but captive patient populations. Two additional approved medicines, Leqvio (cholesterol) and Qfitlia (hemophilia), are commercialized by Novartis and Sanofi, respectively, generating royalties for Alnylam. A key financial feature is an escalating royalty on AMVUTTRA payable to Sanofi (15%–30% of global sales), which pressures gross margins as AMVUTTRA scales. Alnylam's pipeline includes zilebesiran, a twice-annual hypertension treatment in Phase 3 co-developed with Roche targeting a massive patient population, and nucresiran, a next-generation TTR silencer in Phase 3 that carries no Sanofi royalty and could meaningfully improve margins post-2030.