PHILADELPHIA, April 3, 2026 /PRNewswire/ — National plaintiffs’ law firm Berger Montague PC announces that a class action lawsuit has been filed against Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) (“Ultragenyx” or the “Company”) on behalf of investors who purchased common shares of Ultragenyx during the period from August 3, 2023 through December 26, 2025 (the “Class Period”).
Investor Deadline: Investors who purchased Ultragenyx securities during the Class Period may, no later than April 6, 2026, seek to be appointed as a lead plaintiff representative of the class. To learn your rights, CLICK HERE.
Ultragenyx is a Novato, Calif.-based biopharmaceutical company engaged in the acquisition and development of novel products to treat rare diseases.
The complaint alleges that defendants misrepresented the results of the ORBIT and COSMIC Phase 3 programs testing the efficacy of setrusumab as a treatment of Osteogenesis Imperfecta.
According to the lawsuit, investors learned the truth on December 29, 2025, when Ultragenyx disclosed that neither study had met its primary endpoint. This alleged reversal caused the Company’s shares to lose more than 42% of their value in a single trading day.
If you are a Ultragenyx investor and would like to learn more about this action, CLICK HERE or please contact Berger Montague: Andrew Abramowitz at aabramowitz@bergermontague.com or (215) 875-3015, or Caitlin Adorni at cadorni@bergermontague.com or (267)764-4865.
About Berger Montague
Berger Montague is one of the nation’s preeminent law firms focusing on complex civil litigation, class actions, and mass torts in federal and state courts throughout the United States. With more than $2.4 billion in 2025 post-trial judgments alone, the Firm is a leader in the fields of complex litigation, antitrust, consumer protection, defective products, environmental law, employment law, securities, and whistleblower cases, among many other practice areas. For over 55 years, Berger Montague has played leading roles in precedent-setting cases and has recovered over $50 billion for its clients and the classes they have represented. Berger Montague is headquartered in Philadelphia and has offices in Chicago; Malvern, PA; Minneapolis; San Diego; San Francisco; Toronto, Canada; Washington, D.C., and Wilmington, DE.
For more information or to discuss your rights, please contact:
Andrew Abramowitz
Berger Montague
(215) 875-3015
aabramowitz@bergermontague.com
Caitlin Adorni
Berger Montague
(267) 764-4865
cadorni@bergermontague.com
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SOURCE Berger Montague
