Rosen Law Firm Encourages Ultragenyx Investors to Secure Counsel Before Deadline

Investors who purchased Ultragenyx stock between August 2023 and December 2025 may be eligible for compensation.

Mar. 16, 2026 at 4:37am

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Rosen Law Firm, a global investor rights law firm, is reminding purchasers of Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) common stock between August 3, 2023 and December 26, 2025 of the important April 6, 2026 lead plaintiff deadline in a securities class action lawsuit. The lawsuit claims that Ultragenyx provided investors with materially false and misleading information about the potential of its drug setrusumab (UX 143) for treating Osteogenesis Imperfecta.

Why it matters

This case highlights the importance of transparency and accurate disclosures from pharmaceutical companies, especially those developing treatments for rare diseases. Investors rely on these disclosures to make informed decisions, and any misleading information can lead to significant financial losses.

The details

The lawsuit alleges that Ultragenyx made overly positive statements about setrusumab's ability to reduce fracture rates in Osteogenesis Imperfecta patients, while concealing material information that the drug's increase in bone density did not actually correlate to a decrease in fractures. This allegedly caused investors to purchase Ultragenyx stock at artificially inflated prices.

  • The class period is from August 3, 2023 to December 26, 2025.
  • The lead plaintiff deadline is April 6, 2026.

The players

Rosen Law Firm

A global investor rights law firm that is representing investors in this securities class action lawsuit against Ultragenyx.

Ultragenyx Pharmaceutical Inc.

A biopharmaceutical company developing treatments for rare and ultra-rare genetic diseases, including Osteogenesis Imperfecta.

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What they’re saying

“To join the Ultragenyx class action, go to https://rosenlegal.com/submit-form/?case_id=52472 or call Phillip Kim, Esq. toll-free at 866-767-3653 or email case@rosenlegal.com for information on the class action.”

— Phillip Kim, Esq. (Rosen Law Firm)

What’s next

The judge will decide on April 6, 2026 whether to certify the class action lawsuit against Ultragenyx.

The takeaway

This case underscores the need for pharmaceutical companies to be fully transparent with investors about the risks and limitations of their drug candidates, even for treatments targeting rare diseases. Investors rely on accurate information to make informed decisions, and any misleading statements can have serious consequences.