10:36 AM EDT, 07/10/2025 (MT Newswires) -- Ultragenyx Pharmaceutical ( RARE ) shares dropped 27% in recent Thursday trading following a phase 3 study update that disappointed investors, after UX143 missed a key efficacy metric in pediatric and young adult patients with osteogenesis imperfecta, a rare genetic bone disorder.

Developed in collaboration with Mereo BioPharma ( MREO ) , UX143 showed an acceptable safety profile, and the trial will proceed to final analysis, the companies said Wednesday.

"Investors were disappointed" that the annualized fracture rate efficacy hurdle wasn't met, Wedbush Securities said Thursday in a report.

Wedbush lowered its price target on Ultragenyx stock to $35 from $39 and maintained its neutral rating.

"The base business continues to provide a floor in the valuation, but unlocking upside remains dependent on advancing key initiatives," Wedbush said.

Mereo shares fell 35% in recent trading Thursday.

Price: 30.18, Change: -11.27, Percent Change: -27.18