Pomerantz Law Firm Warns Investors of Class Action Against Ultragenyx Pharmaceutical Inc.

Investor Alert: Pomerantz Law Firm Update on Ultragenyx Pharmaceutical Inc.

In a significant development for investors, Pomerantz LLP has announced the initiation of a class action lawsuit against Ultragenyx Pharmaceutical Inc., whose stocks are traded under the ticker symbol RARE. The law firm is calling on investors who incurred losses on their investments in the pharmaceutical company to engage with them for potential legal representation in this lawsuit.

The class action centers on allegations that Ultragenyx and some of its executives may have participated in securities fraud and other unlawful business practices. Investors are urged to contact Pomerantz to determine their eligibility to join this legal action. Specifically, those who acquired Ultragenyx's securities during the stipulated Class Period are encouraged to reach out with their contact details, including postal address and telephone numbers, to facilitate the process.

Key Dates and Legal Procedures

Investors have until April 6, 2026, to submit their requests for court appointment as Lead Plaintiff for the prospective class action. Detailed information related to the lawsuit can be obtained from Pomerantz's website. A copy of the filed Complaint is also accessible, providing further insight into the allegations that underpin this legal challenge.

The class action stems partly from information released on July 9, 2025, wherein Ultragenyx and their development partner Mereo BioPharma Group plc provided updates regarding their clinical trial results. They announced the Phase 3 portion of the Orbit study, aimed at assessing the efficacy of UX143 (setrusumab) in treating osteogenesis imperfecta (OI) in pediatric and young adult populations. Following this announcement, Ultragenyx's stock experienced a marked decline, falling by $10.41, or 25.11%, to close at $31.04 the next day.

Furthermore, on December 29, 2025, the company disclosed that both their Phase III Orbit and Cosmic Studies had failed to demonstrate statistical significance against their primary endpoints, which focused on reducing annualized clinical fracture rates compared to both a placebo and bisphosphonates. This news led to another significant drop in their stock price, decreasing $14.47, or 42.32%, to settle at $34.19.

In light of these occurrences, investors are advised to evaluate their options as the stakes involved in this lawsuit could lead to noteworthy ramifications for both the company and the investors alike.

About Pomerantz LLP

Pomerantz LLP is recognized as a leading firm specializing in corporate, securities, and antitrust class litigation. Established over 85 years ago by Abraham L. Pomerantz, regarded as a pioneer in the class action field, the firm continues to fight for the rights of shareholders and victims of corporate misconduct. Their track record of recovering substantial awards for class members speaks volumes about their commitment and expertise in this area.

For those interested in further pursuing this case, they can reach out to Danielle Peyton at Pomerantz LLP via email or phone. The contact information includes 646-581-9980 (ext. 7980) and toll-free number 888-4-POMLAW for ease of access to those needing assistance.

In conclusion, investors holding shares in Ultragenyx Pharmaceutical Inc. during the Class Period are strongly encouraged to act swiftly to ascertain their legal rights and options in light of the unfolding situation surrounding the potential securities fraud allegations. Time-limited steps must be taken before the specified deadline if they wish to have their concerns addressed in court.