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Why Ultragenyx Pharmaceuticals Stock Is Plummeting Today

The Motley Fool·12/29/2025 20:34:03
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Key Points

  • Ultragenyx Pharmaceuticals reported Phase 3 results for setrusumab, a potential treatment for osteogenesis imperfecta.

  • Several firms have reduced their price targets on Ultragenyx stock.

  • Investors may want to keep their distance from Ultragenyx stock until it provides a Phase 3 readout for Angelman syndrome.

Heading into 2026 on an inauspicious note, Ultragenyx Pharmaceuticals (NASDAQ: RARE), a pharmaceutical company specializing in treatments for rare and ultra-rare genetic diseases, announced disappointing results from its Phase 3 studies for setrusumab (UX143). Add in a flurry of analysts slashing their price targets on Ultragenyx stock, and it's clear why investors are clicking the sell button today.

As of 2:45 p.m. ET, shares of Ultragenyx are down 43.5%.

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Image source: Getty Images.

Promising Phase 2 data didn't translate to Phase 3 success

After providing encouraging Phase 2 results for setrusumab, a monoclonal antibody that Ultragenyx is studying as a treatment for osteogenesis imperfecta (OI), the company reported today that two different studies -- Orbit and Cosmic -- failed to achieve their primary endpoints: reductions in the annualized clinical fracture rates compared to placebo for Orbit study participants or bisphosphonates for Cosmic study participants.

Addressing the Phase 3 results, Dr. Emil Kakkis, CEO of Ultragenyx, stated, "We are surprised and disappointed by these results given the promising data from our Phase 2 study and the lack of approved treatment options available to patients with OI who live with significant pain, disability, and disease burden."

According to UT Southwestern, OI currently affects 20,000 to 50,000 people living in the United States.

In response to the Phase 3 results, several firms slashed their price targets on Ultragenyx stock.

  • Cantor Fitzgerald cut its price target to $84 from $105.
  • Barclays reduced its price target to $50 from $81.
  • Citigroup lowered its price target to $50 from $103.

Should investors buy the dip on Ultragenyx stock?

While the drop in Ultragenyx stock certainly provides a lower entry point for new investors, the more prudent choice right now may be to watch the pharmaceutical stock from the sidelines for the time being and wait for the company to present data from its Phase 3 study of GTX-102, an antisense oligonucleotide therapy for Angelman syndrome.

Citigroup is an advertising partner of Motley Fool Money. Scott Levine has no position in any of the stocks mentioned. The Motley Fool recommends Barclays Plc. The Motley Fool has a disclosure policy.