Alnylam shares tumble 25% as analysts flag uncertainties in its transthyretin franchise

Alnylam Therapeutics saw its stock fall about a quarter on Thursday, closing near $174 after analysts highlighted a trio of uncertainties surrounding its transthyretin (TTR) franchise.

The TTR franchise, which includes the drugs Amvuttra and Onpattro, generated $1.15 billion in revenue for the third quarter, a 59% increase from the same period a year earlier.

Despite the revenue growth, analysts at BMO Capital Markets warned that inventory pressures and pricing challenges could weigh on the business, keeping the stock under pressure. The company’s market value now stands at roughly $23.3 billion, and its shares are down 56% year‑to‑date.

While some investors remain optimistic about Alnylam’s long‑term prospects, the recent cut to revenue guidance has heightened concerns about near‑term performance.