SAN DIEGO , Feb. 27, 2026 /PRNewswire/ -- The law firm of Robbins Geller Rudman & Dowd LLP announces purchasers or acquirers of Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) common stock between August 3, 2023 and December 26, 2025, both dates inclusive (the "Class Period"), have until Monday, April 6, 2026 to seek appointment as lead plaintiff of the Ultragenyx class action lawsuit. Captioned Bailey v. Ultragenyx Pharmaceutical Inc., No. 26-cv-01097 (N.D. Cal.), the Ultragenyx class action lawsuit charges Ultragenyx and certain of Ultragenyx' top executives with violations of the Securities Exchange Act of 1934.

If you suffered substantial losses and wish to serve as lead plaintiff of the Ultragenyx class action lawsuit, please provide your information here:

https://www.rgrdlaw.com/cases-ultragenyx-pharmaceutical-inc-class-action-lawsuit-rare.html

You can also contact attorney J.C. Sanchez of Robbins Geller by calling 800/449-4900 or via e-mail at info@rgrdlaw.com.

CASE ALLEGATIONS: Ultragenyx is a biopharmaceutical company that focuses on the identification, acquisition, development, and commercialization of novel products for the treatment of rare and ultra-rare genetic diseases.

The Ultragenyx class action lawsuit alleges that defendants throughout the Class Period made false and/or misleading statements and/or failed to disclose that: (i) defendants created the false impression that they possessed reliable information pertaining to the effects of setrusumab on patients with variable types of Osteogenesis Imperfecta ("OI"), while also minimizing risk that patients in Ultragenyx' 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; and (ii) in truth, Ultragenyx' 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.

The Ultragenyx class action lawsuit further alleges that on July 9, 2025, Ultragenyx revealed that the Phase III Orbit study failed to achieve statistical significance for the second interim analysis and that Phase III Orbit and Cosmic studies would now be "progressing toward final analysis." On this news, the price of Ultragenyx stock fell more than 25%, according to the complaint.

Then, on December 29, 2025, Ultragenyx announced that both its Phase III Orbit and Cosmic Studies had not "achieved statistical significance against the primary endpoints of reduction in annualized clinical fracture rate compared to placebo or bisphosphonates, respectively." Ultragenyx allegedly attributed the study failure to a "low fracture rate in the placebo group" of Orbit and a trend that fell shy of statistical significance in Cosmic. On this news, the price of Ultragenyx stock fell more than 42%, according to the complaint.

THE LEAD PLAINTIFF PROCESS: The Private Securities Litigation Reform Act of 1995 permits any investor who purchased or acquired Ultragenyx common stock during the Class Period to seek appointment as lead plaintiff in the Ultragenyx class action lawsuit. A lead plaintiff is generally the movant with the greatest financial interest in the relief sought by the putative class who is also typical and adequate of the putative class. A lead plaintiff acts on behalf of all other class members in directing the Ultragenyx investor class action lawsuit. The lead plaintiff can select a law firm of its choice to litigate the Ultragenyx shareholder class action lawsuit. An investor's ability to share in any potential future recovery is not dependent upon serving as lead plaintiff of the Ultragenyx class action lawsuit.

ABOUT ROBBINS GELLER: Robbins Geller Rudman & Dowd LLP is one of the world's leading complex class action firms representing plaintiffs in securities fraud and shareholder rights litigation. Our Firm ranked #1 on the most recent ISS Securities Class Action Services Top 50 Report, recovering more than $916 million for investors in 2025. This marks our fourth #1 ranking in the past five years. And in those five years alone, Robbins Geller recovered $8.4 billion for investors – $3.4 billion more than any other law firm. With 200 lawyers in 10 offices, Robbins Geller is one of the largest plaintiffs' firms in the world, and the Firm's attorneys have obtained many of the largest securities class action recoveries in history, including the largest ever – $7.2 billion – in In re Enron Corp. Sec. Litig. Please visit the following page for more information:

https://www.rgrdlaw.com/services-litigation-securities-fraud.html

Past results do not guarantee future outcomes.
Services may be performed by attorneys in any of our offices. 

Contact:
            Robbins Geller Rudman & Dowd LLP
            J.C. Sanchez
            655 W. Broadway, Suite 1900, San Diego, CA 92101
            800-449-4900
            info@rgrdlaw.com 

View original content to download multimedia:https://www.prnewswire.com/news-releases/ultragenyx-pharmaceutical-inc-investors-with-substantial-losses-have-opportunity-to-lead-class-action-lawsuit---rare-302699192.html

SOURCE Robbins Geller Rudman & Dowd LLP