Rare Investors Have Opportunity to Lead Ultragenyx Pharmaceutical Securities Fraud Lawsuit

Rosen Law Firm announces class action lawsuit against Ultragenyx Pharmaceutical Inc. for alleged securities fraud

Published on Feb. 12, 2026

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Rosen Law Firm, a global investor rights law firm, has announced a class action lawsuit on behalf of purchasers of Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) common stock between August 3, 2023 and December 26, 2025. The lawsuit alleges that Ultragenyx provided investors with materially false and misleading information about the potential of its drug setrusumab (UX 143) for treating Osteogenesis Imperfecta (OI), causing shareholders to purchase the stock at artificially inflated prices.

Why it matters

This lawsuit highlights the importance of transparency and accurate disclosures by pharmaceutical companies, especially those developing drugs for rare diseases. Investors rely on these disclosures to make informed decisions, and any alleged misrepresentations can have significant financial consequences.

The details

According to the lawsuit, Ultragenyx allegedly provided investors with overly positive statements about setrusumab's ability to reduce the annualized fracture rate in OI patients, while concealing material adverse facts about the drug's true potential and the risks inherent in the study protocols. The lawsuit claims these statements caused Ultragenyx's stock to trade at artificially inflated prices, and when the true details emerged, investors suffered damages.

  • The class period is from August 3, 2023 to December 26, 2025.
  • Investors have until April 6, 2026 to move the court to serve as lead plaintiff in the class action lawsuit.

The players

Rosen Law Firm

A global investor rights law firm that is representing the class of Ultragenyx shareholders in the lawsuit.

Ultragenyx Pharmaceutical Inc.

A biopharmaceutical company that is the defendant in the securities fraud lawsuit.

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What they’re saying

“We encourage investors to select qualified counsel with a track record of success in leadership roles. Often, firms issuing notices do not have comparable experience, resources, or any meaningful peer recognition. Be wise in selecting counsel.”

— Laurence Rosen, Founding Partner, Rosen Law Firm (PRNewswire)

What’s next

Investors have until April 6, 2026 to move the court to serve as lead plaintiff in the class action lawsuit.

The takeaway

This lawsuit highlights the importance of pharmaceutical companies providing accurate and transparent information to investors, especially for drugs targeting rare diseases. Investors should be cautious and select experienced legal counsel when considering participation in securities fraud class actions.