Highlights

  • Ultragenyx shares fell 43.5% following Phase 3 studies failing to meet primary endpoints.
  • Analysts slashed price targets, signaling market concerns over short-term stock performance.
  • Investors await additional data from the Angelman syndrome Phase 3 trial for future guidance.

Ultragenyx Pharmaceuticals (NASDAQ:RARE), a company focusing on treatments for rare genetic diseases, reported Phase 3 results for setrusumab (UX143), a monoclonal antibody for osteogenesis imperfecta (OI), that did not achieve primary endpoints.

The Orbit and Cosmic studies were designed to measure reductions in annualized clinical fracture rates. The Orbit study compared setrusumab to placebo, while the Cosmic study compared the drug to bisphosphonates. Both trials failed to meet these primary objectives.

Previously, Phase 2 data for setrusumab had shown promising results, creating high expectations for the Phase 3 trials.

Market Focus on Future Data
Investors are closely monitoring the Phase 3 trial for Angelman syndrome, which could influence the company’s near-term outlook. Until data from this trial becomes available, the market reaction to Ultragenyx stock is expected to remain sensitive to updates from ongoing clinical programs.

Share Performance
On December 29, 2025, Ultragenyx Pharmaceuticals closed at 19.72 USD, down 42.32% from the previous session. The stock opened at 19.32 USD, reached a high of 20.49 USD, and a low of 18.41 USD. After-hours trading showed a slight increase to 19.95 USD. The company’s market capitalization stood at 190.25Cr USD.