Alnylam's Portfolio Diversification Questioned as Amvuttra Dependency Remains

What happened

A Zacks article questions whether Alnylam's other products (Givlaari, Oxlumo, Leqvio) can meaningfully diversify from Amvuttra, which dominates revenue. The DeepValue master report confirms Amvuttra is the primary growth driver, with the TTR franchise effectively a single-product story. While the broader portfolio grew, combined net product revenue for the Rare franchise was a fraction of Amvuttra's Q3'25 $685M. The report highlights that Amvuttra's ATTR-CM expansion is key, but competitive pressure from BridgeBio's Attruby and a subpoena overhang add risk. As such, the company's dependence on Amvuttra is unlikely to ease in the near term, and the investment thesis hinges on Amvuttra's execution rather than portfolio breadth.

Implication

For long-term investors, the diversification narrative is premature. While Leqvio and the rare disease franchise have potential, they are not yet material enough to offset a potential Amvuttra miss. The thesis remains unchanged: wait for proof of Amvuttra's scaling trajectory and resolution of the subpoena before committing significant capital.

Thesis delta

The article and report together reinforce the existing thesis rather than shift it. Alnylam's portfolio breadth is a long-term option, not a near-term safety net. The core risk/reward still depends on Amvuttra's net price and share capture in ATTR-CM.