Ultragenyx Pharmaceutical Faces Class Action Lawsuit

Investors have until April 6, 2026, to file for lead plaintiff status in securities fraud case

Published on Feb. 25, 2026

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A securities fraud class action lawsuit has been filed against Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) on behalf of investors who purchased or acquired the company's common stock between August 3, 2023, and December 26, 2025. The lawsuit alleges that Ultragenyx made false and/or misleading statements and/or failed to disclose material information about its drug setrusumab, leading to a significant stock price drop when the company revealed that its Phase III studies had not achieved statistical significance against primary endpoints.

Why it matters

This lawsuit highlights the importance of transparency and accurate disclosures in the pharmaceutical industry, where investors rely on companies to provide reliable information about the progress and potential of their drug candidates. The allegations raise concerns about Ultragenyx's conduct and the potential impact on investors who suffered losses as a result.

The details

The complaint alleges that Ultragenyx created a false impression about the effects of setrusumab on patients with Osteogenesis Imperfecta, while minimizing the risk that the Phase III Orbit study would fail to achieve a statistically significant reduction in annualized fracture rate. The company allegedly failed to convey the risk associated with basing the interim analysis benchmark on Phase II results that lacked a placebo control group for appropriate comparison.

  • The class period is from August 3, 2023, through December 26, 2025.
  • Investors have until April 6, 2026, to file for lead plaintiff status.

The players

Ultragenyx Pharmaceutical Inc.

A biopharmaceutical company that develops and commercializes novel products for the treatment of rare and ultra-rare genetic diseases.

Kessler Topaz Meltzer & Check, LLP

A leading U.S. plaintiff-side law firm focused on securities-fraud class actions and global investor protection.

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What they’re saying

“If you purchased or acquired Ultragenyx Pharmaceutical Inc. common stock and have lost money on your investment, you are encouraged to contact KTMC attorney Jonathan Naji, Esq. at: (484) 270-1453 info@ktmc.com”

— Jonathan Naji, Attorney, Kessler Topaz Meltzer & Check, LLP (www.ktmc.com)

What’s next

The judge in the case will decide on April 6, 2026, whether to allow the lawsuit to proceed as a class action.

The takeaway

This case highlights the importance of pharmaceutical companies providing accurate and transparent information to investors, especially regarding the progress and potential of their drug candidates. Investors who suffered losses due to Ultragenyx's alleged misconduct may be able to seek recovery through the class action lawsuit.