Alnylam’s shares fell sharply after the company cut 2026 financial guidance for its transthyretin (TTR) amyloidosis franchise, pointing to demand that “normalized” after an early Amvuttra launch spike. The company lowered its expected 2026 revenue for Amvuttra and Onpattro by about $200 million, to $4.2 billion–$4.5 billion from its prior $4.4 billion–$4.7 billion range. Analysts framed the move as a “one-two punch” because it adds to previously renewed scrutiny in the TTR cardiomyopathy competition backdrop, including other drugs such as Pfizer’s Vyndamax and BridgeBio’s Attruby. Investors also remain focused on late-cycle trial readouts tied to Alnylam’s broader TTR positioning, with a key presentation expected in late August. While quarterly results still showed Amvuttra sales of $1.01 billion (slightly below consensus), the guidance reduction is likely to intensify debate over long-term share and trajectory in a market that is becoming increasingly crowded.