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LOS ANGELES, Dec. 30, 2025 (GLOBE NEWSWIRE) -- The Portnoy Law Firm advises Ultragenyx Pharmaceutical, Inc. (“Ultragenyx" or the "Company") (NASDAQ: RARE) investors that the firm has initiated an investigation into possible securities fraud, and may file a class action on behalf of investors.
Investors are encouraged to contact attorney Lesley F. Portnoy, by phone 844-767-8529 or email: lesley@portnoylaw.com, to discuss their legal rights, or join the case via https://portnoylaw.com/ultragenyx-pharmaceutical-inc. The Portnoy Law Firm can provide a complimentary case evaluation and discuss investors’ options for pursuing claims to recover their losses.
On December 29, 2025, Ultragenyx announced the results from both its Phase III Orbit and Cosmic studies, both focused on the effectiveness of setrusumab (UX143) in Osteogenesis Imperfecta. Both studies failed to achieve their primary endpoint of a reduction in annualized clinical fracture rate compared to placebo (in the Orbit study) and biophosphonates (in the Cosmic). While both studies achieved improvements in their secondary endpoints of improving patients' bone material density, that secondary result failed to correlate to a statistically significant reduction in fractures in either study. Ultragenyx further disclosed that it "will promptly define and implement significant expense reductions”. In direct response to this news, Ultragenyx's stock price fell by $14.87 (43.49%) per share to open at $19.32 per share on December 29, 2025. Ultragenyx's decline has dropped the stock to its new 52-week low, significantly below the prior low of $25.81
The Portnoy Law Firm represents investors in pursuing claims caused by corporate wrongdoing. The Firm’s founding partner has recovered over $5.5 billion for aggrieved investors. Attorney advertising. Prior results do not guarantee similar outcomes.
Lesley F. Portnoy, Esq.
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