Alnylam Shares Slide Amid Revenue Growth Concerns

The company's stock dropped 25 percent as market competition and pending 340B pricing rule changes create near-term volatility.

Updated on Oct. 30, 2026 in Biotech

Bold flat-color editorial illustration of a clinical glass vial, symbolizing pharmaceutical market volatility and regulatory uncertainty. — Alnylam Pharmaceuticals shares fell 25 percent on Tuesday as the company contends with market competition and potential 340B drug pricing rule changes. AI Illustration. Upload story photo >

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Alnylam Pharmaceuticals shares fell 25 percent on October 29, 2026, closing at $174 as the company faces market share competition and uncertainty regarding upcoming 340B drug pricing rules. Executives acknowledged slower-than-expected adoption for its Amvuttra franchise, which treats transthyretin-mediated amyloidosis.

Why it matters

The company is navigating a transition in the competitive market for amyloidosis treatments while providers delay ordering due to looming federal pricing adjustments. This volatility underscores the impact of the 340B program updates on pharmaceutical revenue projections as January 2027 approaches.

Alnylam's transthyretin franchise reached $1.15 billion in Q3 revenue, growing 59 percent year-over-year. However, Truist Securities estimates that 15 to 20 percent of Amvuttra volume remains directly exposed to the 340B drug pricing rule changes effective January 1, 2027.

The players

Alnylam Pharmaceuticals

A biopharmaceutical company focused on RNA interference-based therapies and the developer of the Amvuttra drug franchise.

Yvonne Greenstreet

The CEO of Alnylam who acknowledged current dissatisfaction with the growth rate of the company's core drug franchise.

BridgeBio Pharma

A commercial-stage biopharmaceutical company competing directly with Alnylam for market share in the treatment of amyloidosis.

Pfizer

A multinational pharmaceutical corporation that serves as a market competitor in the transthyretin-mediated amyloidosis space.

Truist Securities

A financial services firm providing market analysis on drug volume exposure to federal pricing policy shifts.

The details

Amvuttra is a therapeutic treatment for transthyretin-mediated amyloidosis, a condition where abnormal protein buildup causes organ damage. Alnylam is currently focused on capturing the two-thirds of potential prescribers who have not yet initiated a prescription to drive growth. The firm's revenue visibility is further complicated by competitors like BridgeBio Pharma and Pfizer, who are also vying for market share in the amyloidosis space.

2022: Amvuttra received FDA approval for ATTR-PN.
March 2025: Amvuttra received FDA approval for ATTR-CM.
October 29, 2026: Alnylam shares declined by 25 percent.
January 1, 2027: 340B drug pricing rule update becomes effective.
February 2027: Alnylam will release 2027 financial guidance.

The Tech Race

The firm is currently struggling to maintain dominance against competitors like BridgeBio Pharma and Pfizer in the growing amyloidosis treatment market. Market volatility stems from how these commercial pipelines interact with the regulatory requirements of the 340B drug pricing program.

Investors and stakeholders can expect further clarity on the company's fiscal trajectory in February 2027 when Alnylam releases its 2027 guidance. The immediate concern for providers and patients is the potential shift in ordering workflows due to the 340B rule update effective January 1, 2027.

The takeaway

Alnylam is navigating a difficult transition period defined by competitive pressure and regulatory uncertainty that has cut its year-to-date stock value by 56 percent. Observers should track the upcoming financial guidance in February 2027 to see if the company recovers its growth rate.