RARE Stock Heads For Record Low: Angelman Trial Miss Leads To Wall Street Downgrades – This Analyst Sees Another Problem Ahead

• Ultragenyx’s GTX-102 failed to meet its main goal of improving cognitive function in children aged 4 to 17.
• William Blair does not expect any major event over the next 12 months that could significantly change Ultragenyx’s valuation.
• Evercore ISI downgraded Ultragenyx to ‘In Line’ from ‘Outperform’ and slashed its price target to $16 from $34.

Ultragenyx Pharmaceutical (RARE) was in the spotlight on Thursday after its experimental Angelman syndrome therapy failed a key late-stage trial, prompting analyst downgrades and raising fresh concerns about the company’s growth outlook.

RARE shares were down 45% in pre-market trading and are on track to hit their all-time lows.

William Blair Downgrades RARE After Late-Stage Miss

William Blair downgraded Ultragenyx to ‘Market Perform’ from ‘Outperform’ after the Phase 3 Aspire study of Apazunersen, also known as GTX-102, failed to meet its main goal of improving cognitive function in children aged 4 to 17. The study also missed key secondary endpoints, though safety remained consistent with earlier studies.

The study enrolled 129 children with Angelman syndrome, a rare genetic brain disorder that can cause severe developmental delays, speech and movement difficulties, and seizures. Ultragenyx estimates roughly 60,000 patients live in commercially accessible markets.

Ultragenyx’s Other Angelman Study To Be Affected

William Blair said the failure also has negative implications for the ongoing Aurora study and sees no major value-driving catalysts over the next 12 months. Aurora is testing GTX-102 in a broader group, including younger and adult patients, as well as Angelman patients with genetic types not covered by Aspire.

Ultragenyx expects Aurora enrollment to finish in the second half of 2026. ClinicalTrials.gov lists completion by January 2030.

Following Aspire’s failure, Ultragenyx said it will evaluate the future of the overall GTX-102 program and plans significant expense reductions.

William Blair does not expect any major event over the next 12 months that could significantly change Ultragenyx’s valuation.

Evercore Calls It A ‘Clean Fail’

Evercore ISI downgraded Ultragenyx to ‘In Line’ from ‘Outperform’ and slashed its price target to $16 from $34, describing Aspire as a “clean fail.”

The firm also pointed to Ultragenyx's high spending, Crysvita’s eventual loss of exclusivity and its reliance on first-generation AAV8/9 systemic gene therapies targeting relatively small patient populations. Crysvita is used to treat rare genetic and hormone-related bone diseases.

Fresh Questions Over Ultragenyx Pipeline 

Baird analyst Jack Allen downgraded Ultragenyx and expects limited investor interest given unknowns surrounding Crysvita's commercial longevity and Ultragenyx's limited pipeline.

JPMorgan sees fundamental value in the commercial business, which it values in the mid-$20s per share range. However, shifting sentiment on Ultragenyx shares and getting fundamental pull-through from new launches will take time, the analyst wrote in a research note.

Following the failure of Aspire, Wells Fargo believes the catalyst path leaves little room for near-term upside.

RARE Stock: Flurry Of Price Target Cuts

Retail Remains Confident Despite Crash

Despite the pre-market slump, retail sentiment surrounding RARE on Stocktwits flipped to ‘extremely bullish’ from ‘bearish’ a day earlier, amid a 3,900% increase in message volume.

One bullish user highlighted the company’s pipeline and expected profitability. The FDA is expected to decide on Ultragenyx’s resubmitted application seeking accelerated approval for UX111, its therapy for Sanfilippo syndrome Type A (a genetic brain disease), by Sept. 19, 2026.

Another user urged buying and holding the stock until September 19.

The stock is down more than 35% so far this year.

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