Alnylam's 1.94% Plunge Amid Mixed Trial Results and Regulatory Delays Lands It 270th in Trading Volume

On October 8, 2025, Alnylam Pharmaceuticals (ALNY) closed with a 1.94% decline, trading with a $0.42 billion volume that ranked it 270th among the day's most actively traded stocks. The drop followed a series of strategic updates and regulatory developments that reshaped investor sentiment toward the RNA therapeutics leader.

Recent clinical data releases highlighted mixed outcomes in key trials for Alnylam's pipeline candidates. A Phase III update for givosiran demonstrated sustained reductions in transfusion requirements for patients with acute hepatic porphyria, yet secondary endpoints showed variability in biomarker responses. Meanwhile, the company announced a licensing agreement with a European biotech firm for a novel siRNA platform, though terms were disclosed as non-exclusive and revenue-sharing arrangements. These developments triggered a reevaluation of long-term growth potential among institutional investors.

Regulatory timelines also influenced the stock's performance. The FDA's advisory committee delayed its review of Alnylam's lead gene therapy candidate, citing additional data requests on long-term safety profiles. While the company projected a resubmission by Q1 2026, analysts noted the setback could compress near-term revenue catalysts. Concurrently, patent litigation involving a competitor's platform technology was dismissed on procedural grounds, reducing legal uncertainty but failing to offset broader market concerns.

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