Ultragenyx Pharma Faces Investor Lawsuit

The lawsuit centers on allegations of misleading statements regarding the potential of setrusumab, a drug being tested for Osteogenesis Imperfecta, a genetic disorder that results in brittle bones. The legal filings claim Ultragenyx made overly optimistic statements about the drug's ability to reduce fracture rates. At the heart of the matter are the Phase III Orbit and Cosmic clinical trials. The lawsuit alleges that the company downplayed risks and created a false impression of reliable data, even though the Phase II results used to set expectations lacked a placebo control group for accurate comparison. On December 29, 2025, Ultragenyx disclosed that neither the Orbit nor the Cosmic study had met its primary goal of achieving a statistically significant reduction in the rate of clinical fractures. This news contradicted the company's prior positive outlook. The market's reaction to the trial results was swift and severe. Ultragenyx's stock price plummeted by over 42%, falling from a closing price of $34.19 on December 26, 2025, to $19.72 per share on December 29, 2025. The class-action lawsuit, filed in the Northern District of California, seeks to recover financial losses for investors who purchased the company's stock during the period of allegedly misleading statements. Investors have until April 6, 2026, to file to be a lead plaintiff in the case.