RARE Stock Crashes In Worst Day Ever — ‘Pharma Bro’ Martin Shkreli Calls It ‘Very Cheap,’ Floats BioMarin Buyout

• Martin Shkreli called RARE stock “very cheap” and said BioMarin and other rare-disease drugmakers should explore acquiring Ultragenyx.
• RARE stock's selloff followed the failure of Apazunersen in a Phase 3 Angelman syndrome trial, where the drug missed both its primary and secondary endpoints.
• Analysts said the investment case now depends on commercial execution, margin expansion, and upcoming pipeline catalysts.

Shares of Ultragenyx Pharmaceutical (RARE) suffered their worst trading day on record and closed at an all-time low on Thursday after its Angelman syndrome treatment failed a key trial, prompting sweeping Wall Street target cuts and takeover speculation from former pharma executive Martin Shkreli.

RARE stock plunged about 44% to $14.85 on Thursday, wiping out nearly half its value in one session.

Shkreli Floats BioMarin Buyout 

“$RARE is very cheap,” Shkreli said on X. He argued that BioMarin Pharmaceutical (BMRN) and other rare-disease companies “should explore buying the company.” Shkreli, widely known as “Pharma Bro,” also claimed that the setback was foreseeable, saying “everyone and their brother with three months of med school/Shkreli training knew this trial would fail.”

BioMarin and Ultragenyx both develop and commercialize treatments for genetically defined rare diseases, with overlap in metabolic disorders, enzyme-replacement therapies, gene therapy and the specialist physicians they serve. 

Ultragenyx shares crashed after its Phase 3 Aspire trial of Apazunersen, formerly GTX-102, failed both its primary and secondary endpoints. Patients receiving the drug showed no meaningful improvement over the control group in cognition or across a broader measure of Angelman symptoms. 

Apazunersen was designed to activate a normally silent copy of the UBE3A gene. Angelman syndrome is a rare genetic brain disorder that can cause cognitive and movement impairments, seizures, balance problems and severe speech limitations. Ultragenyx estimates it affects about 60,000 people in accessible markets, with no approved treatment for its underlying cause. 

The drug’s safety profile remained consistent with its Phase 1/2 program, but Ultragenyx said it will now assess the program’s future and implement “significant expense reductions.”  The company said it will refocus on its expanding commercial portfolio, including recently approved Genglycos for glycogen storage disease type Ia, the potential approval of UX111 for Sanfilippo syndrome and geographic expansion of existing products. 

Wall Street Slashes RARE Targets 

Wall Street stripped the Angelman program from valuation models after the failure. RBC said the lack of numerical disclosure and limited positive framing suggested the drug may have produced no efficacy signal, while cautioning against automatically applying that conclusion to Ionis Pharmaceuticals’ (IONS) competing program due to differences in the molecules and dosing.

TD Cowen called the failure unfortunate but not surprising given already-low expectations. Meanwhile, Jefferies said the outcome was surprising but added that Ultragenyx’s commercial franchise and broader potential was intact. Cantor Fitzgerald said it understood the trial’s risks but had hoped for better results.

Wedbush removed Apazunersen from its estimates and revised its spending assumptions. Morgan Stanley said the investment debate will now shift toward commercial execution, margin expansion and the remaining pipeline, warning that a strategic reset will take time. 

How Do Retail Traders Feel About RARE?

On Stocktwits, retail sentiment for RARE jumped to ‘extremely bullish’ from ‘neutral’ levels a week ago amid a 9,200% surge in message volumes over the past week. The ticker’s watcher base has also jumped nearly 40% in a month and 27% in a week.

One user said, “all things considered, the call options appear cheap and I'd say the most prudent way to play this if you want to protect yourselves should it experience another big leg down instead. I'll give this a speculative BUY rating.”

Another user said, “$RARE overreacting. They still generating $740 revenue and have 5 commercialized drugs and q drug to be launched in Q4 and 1 drug has a PDUFA on 9/19/2026. Also, institutional ownership is 128%. This will open >$22|

RARE stock has declined 53% over the past year. 

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