Regulatory class action lawsuit

Pomerantz LLP Sues Ultragenyx Over Failed Trials

Analysis based on 49 articles · First reported Jan 28, 2026 · Last updated Mar 15, 2026

Sentiment

-70

Attention

Articles

Market Impact

Direct

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Market Impact

The class action lawsuit against Ultragenyx, stemming from failed clinical trials, is expected to negatively impact investor confidence in the biotechnology sector, particularly for companies with drugs in late-stage development. Ultragenyx's stock has already experienced significant declines, reflecting the market's negative reaction to the trial failures and the subsequent legal action.

Biotechnology Pharmaceuticals Legal Services

Event Summary

Pomerantz LLP has filed a class action lawsuit against Ultragenyx Inc. on behalf of investors, alleging securities fraud. This legal action follows significant drops in Ultragenyx's stock price after the company and its partner, Mereo BioPharma Group, announced that their Phase III Orbit and Cosmic Studies for UX143 (setrusumab) failed to achieve primary endpoints. The stock fell 25.11% on July 10, 2025, and an additional 42.32% on December 29, 2025, after these announcements. Investors who purchased Ultragenyx securities during the Class Period have until April 6, 2026, to seek lead plaintiff status.

Key Actions

100 Ultragenyx announced Phase 3 Orbit and Cosmic studies failed

100 Ultragenyx stock price fell by 42.32%

100 Ultragenyx announced failure of Phase III Orbit and Cosmic Studies

100 Ultragenyx announced Phase III Orbit and Cosmic Studies failed

95 Ultragenyx stock price fell

90 Pomerantz LLP filed a class action lawsuit Ultragenyx

90 Pomerantz LLP filed class action lawsuit Ultragenyx

80 Ultragenyx stock price fell by 25.11%

+ 2 more actions View on Dashboard

Entities Involved

stock

Ultragenyx

Ultragenyx is facing a class action lawsuit due to alleged securities fraud, following significant drops in its stock price after failed clinical trials for UX143 (setrusumab). The company's stock fell 25.11% and 42.32% on two separate occasions due to negative news.

Importance 100 Sentiment -90

priv

Pomerantz LLP

Pomerantz LLP has filed a class action lawsuit against Ultragenyx, representing investors who purchased Ultragenyx securities during the Class Period. This action positions Pomerantz LLP as a key player in seeking damages for alleged securities fraud.

Importance 70 Sentiment 50

stock

Mereo BioPharma Group

Mereo BioPharma Group was a development partner with Ultragenyx on the UX143 (setrusumab) program, which failed to meet its primary endpoints in Phase III trials. This failure negatively impacts Mereo BioPharma Group's reputation and potential future revenues from the drug.

Importance 60 Sentiment -50

per

Danielle Peyton

Danielle Peyton is a contact person at Pomerantz LLP for investors interested in joining the class action lawsuit against Ultragenyx Pharmaceutical Inc. Her role is administrative in facilitating investor participation.

Importance 20 Sentiment 10

exch

Nasdaq

Nasdaq is the exchange where Ultragenyx's shares are traded. The significant stock price drops of Ultragenyx were observed on this exchange.

Importance 10 Sentiment 0

Relationships

Pomerantz LLP related ↔ Ultragenyx

Ultragenyx related ↔ Mereo BioPharma Group

Danielle Peyton related ↔ Pomerantz LLP

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