Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) Securities Fraud Class Action

Case Background:
This is a federal securities fraud class action lawsuit filed on behalf of those who purchased or otherwise acquired Ultragenyx Pharmaceutical Inc. (“Ultragenyx”) (NASDAQ: RARE) common stock between August 3, 2023, to December 26, 2025, inclusive (the “Class Period”).

The complaint alleges that, throughout the Class Period, Defendants made false and/or misleading statements and/or failed to disclose that: (1) Ultragenyx created the false impression that they possessed reliable information pertaining to the effects of the company’s drug, setrusumab, on patients with variable types of Osteogenesis Imperfecta, while also minimizing risk that patients in Ultragenyx’s Phase III Orbit study would fail to achieve a statistically significant reduction in annualized fracture rate (“AFR”), such that the second interim analysis could be performed and presented to the investing public; (2) in truth, Ultragenyx’s optimism in the Phase III Orbit study’s results and interim analysis benchmark were misplaced because Ultragenyx failed to convey the risk associated with basing such threshold figures on Phase II results that had no placebo control group for appropriate comparison and thus had not ruled out that the reduction in AFR from that study could merely be triggered by an increased standard of care and the placebo effect of being provided a novel treatment; and (3) as a result of the foregoing, Defendants’ statements about the company’s business, operations, and prospects were materially false and misleading and/or lacked a reasonable basis at all relevant times.

Current Status of Case:
On April 6, 2026, Motions to Appoint Lead Plaintiff and Lead Counsel were filed, and are currently pending decision before the Court. This action is ongoing.

If you wish to discuss this action or have any questions, please contact Kessler Topaz Meltzer & Check, LLP: Jon Naji, Esq. (484) 270-1453; toll-free at (844) 887-9500; or via e-mail at [email protected]. If you would like additional information about the suit, please click on the link “Submit Your Information” above and fill out the form as promptly as possible.

ABOUT KESSLER TOPAZ MELTZER & CHECK, LLP:
Kessler Topaz Meltzer & Check, LLP (KTMC) is a leading U.S. plaintiff-side law firm focused on securities-fraud class actions and global investor protection. The firm represents individual investors as well as institutions, such as major pension funds, asset managers, and international investors. KTMC has led some of the largest recoveries in securities litigation and has been recognized by peers and the legal media with numerous accolades, including The National Law Journal’s Plaintiff’s Hot List and Trailblazers in Plaintiffs’ Law, BTI Consulting Group’s Honor Roll of Most Feared Law Firms, The Legal Intelligencer’s Class Action Firm of the Year, Lawdragon’s Leading Plaintiff Financial Lawyers, and Law360’s Titans of the Plaintiffs Bar. The firm operates globally with offices in Pennsylvania and California. KTMC has recovered over $25 billion for our clients and the classes they represent.