Insmed Shares Dive 9.49% as Failed Trial, Legal Probe Weigh on Biopharma Giant

The share price fell to its lowest level since October 2025 today, with an intraday decline of 3.08%.

Insmed’s recent slide follows a pivotal setback in its drug pipeline and a legal investigation. On Dec. 17, 2025, the company announced its Phase 2b BiRCh trial for brensocatib in chronic rhinosinusitis without nasal polyps (CRSsNP) failed to meet primary and secondary endpoints, leading to the discontinuation of the program. This marked the end of a key therapeutic candidate and triggered a 16.08% single-day drop in shares the following day. The failure,

coupled with a securities fraud probe by Pomerantz LLP launched on Jan. 15, 2026, has compounded investor concerns about the company’s growth trajectory and governance practices.

As a biopharma firm with a limited portfolio, Insmed’s reliance on brensocatib’s success left its stock vulnerable to volatility. The drug’s discontinuation removes a major revenue and market-share opportunity, while the legal inquiry—focused on potential pre-trial disclosures—adds reputational and financial risks. With no high-potential pipeline replacements highlighted, the company faces scrutiny over its ability to pivot strategically. The ongoing decline, now a 9.49% drop over four trading days, reflects a loss of confidence in its near-term innovation capacity and operational resilience.