Alnylam Q4 Earnings Beat, Sales Miss Underscores Execution Fragility Amid Scaling Risks

What happened

Alnylam's Q4 earnings surpassed estimates, but sales missed expectations despite 85% year-over-year revenue growth, primarily fueled by robust Amvuttra demand in ATTR-CM. The stock declined on the news, reflecting market unease with the sales shortfall and heightened sensitivity to quarterly performance, as highlighted in the DeepValue report. This aligns with prior warnings that ALNY's valuation at $331 assumes smooth execution of its $4.9B–$5.3B FY2026 guidance, leaving little room for error. Persistent overhangs include a subpoena on government price reporting, competitive pressure from BridgeBio's Attruby, and payer policy risks that could disrupt net pricing. Despite operational progress, the reaction confirms that investors are scrutinizing cadence more than growth, underscoring the precarious balance between scaling and stability.

Implication

The Q4 results expose the brittleness of Alnylam's premium valuation, which banks on flawless Amvuttra scaling to meet ambitious revenue targets. Even small deviations, like this sales miss, trigger outsized stock reactions, emphasizing the market's low tolerance for execution slips amid high expectations. This fragility is exacerbated by ongoing legal scrutiny from a subpoena that could impact gross-to-net economics and by intensifying competition in ATTR-CM from BridgeBio's Attruby. Investors must closely monitor quarterly revenue cadence against FY2026 guidance and watch for signs of payer policy tightening or competitive share losses. Until these risks subside or the stock approaches a more attractive entry near $300, staying on the sidelines offers better risk-adjusted returns, as the downside from pricing or access shocks outweighs near-term upside.

Thesis delta

The new information validates the existing thesis that ALNY is priced for perfection and highly sensitive to quarterly execution, but it does not alter the core investment call. It reinforces the need for vigilance on sales cadence and risk factors like the subpoena and competition, without shifting the base case probability or implied value. Thus, the 'WAIT' rating and re-assessment window of 3-6 months remain unchanged, emphasizing patience for clearer proof of scaling sustainability.