Ultragenyx Pharmaceutical Inc.
Case Overview
| Lead Plaintiff Deadline: | Lead Plaintiff Deadline: 04/06/2026 |
| Status: | Status: Investigating |
| Company Name: | Company Name: Ultragenyx Pharmaceutical Inc. |
| Court: | Court: Northern District of California |
| Case Number: | Case Number: 3:26cv01097 |
| Class Period: | Class Period: 08/03/2023 - 12/26/2025 |
| Ticker: | Ticker: RARE |
| Related Attorneys: | Lead Attorneys: Thomas W. Elrod |
| Related Practices: | Related Practices: Securities |
The law firm of Kirby McInerney LLP announces that a class action lawsuit has been filed on behalf of investors who acquired (“” or the “Company”) (NASDAQ: RARE) securities during the period of August 3, 2023 through December 26, 2025, inclusive (“the Class Period”).
According to the complaint, defendants provided overwhelmingly positive statements to investors while, at the same time, disseminating materially false and misleading statements and/or concealing material adverse facts concerning the true state of setrusumabs potential and the true risk inherent in the study protocols put forth; notably, that, while setrusumab does increase material bone density, this increase does not correlate to a decrease in annualized fracture rates or otherwise the Phase III Orbit and Cosmic studies were much less likely to be able to demonstrate such a link than management claimed.
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. The Company 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. Following this news, the price of Ultragenyx common stock declined dramatically. On this news, the price of Ultragenyx shares declined by $14.47 per share, or approximately 42.3%, from $34.19 per share on December 26, 2025 to close at $19.72 on December 29, 2025.