Archived Investigations

Ultragenyx Pharmaceutical Inc. (NasdaqGS: RARE)

Company Name:Ultragenyx Pharmaceutical Inc.
Stock Symbol:Ultragenyx Pharmaceutical Inc. (NasdaqGS: RARE)
Court:Northern District of California
Class Period Start:08/03/2023
Class Period End (inclusive):12/26/2025
Filing Deadline:The deadline has passed.
February 5, 2026

The lawsuit seeks to recover losses on behalf of investors of Ultragenyx who were adversely affected by alleged securities fraud between August 3, 2023 and December 26, 2025.

On December 26, 2025, the Company announced the “results from the Phase 3 Orbit and Cosmic studies for setrusumab (UX143) in Osteogenesis Imperfecta” disclosing that both its Phase III Orbit and Cosmic studies failed to demonstrate that setrusumab triggered a statistically significant reduction in annualized fracture rates for patients with osteogenesis imperfecta, and, as a result the Company “is evaluating its planned operations and will promptly define and implement significant expense reductions.”  On this news, the price of Ultragenyx’s shares fell approximately 42%, from $34.19 per share on December 26, 2025 to $19.72 per share on December 29, 2025.

The case is Steven Bailey v. Ultragenyx Pharmaceutical Inc., et al., No. 26-cv-01097.

Click here to read the first filed complaint.

Recent Investigations

Recent Victories

Chancery Sustains KSF’s Claims in Trecora Merger Litigation

Vice Chancellor Nathan A. Cook denied the defendants’ motion to dismiss KSF's class action complaint in its entirety. KSF's complaint, filed in the Delaware Court of Chancery on behalf of former stockholders of Trecora Resources Inc., alleges that Trecora’s directors breached their duty of loyalty in connection with the sale of Trecora.