What Has The Market Missed In Acadia Pharmaceuticals Stock’s Drop?
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One product stands out at Acadia Pharmaceuticals (ACAD): DAYBUE, its Rett syndrome treatment, and it may be what the market has missed in the drop. You probably still know Acadia for NUPLAZID, but its second drug is now growing faster. Yet the stock lost 43.9% in the three months to November 9, 2026, while the S&P 500 lost 2.1%. It fell 22.3% on November 9 alone. That is the contradiction. So, how big has DAYBUE become?
DAYBUE Is Now About Two-Fifths Of Acadia’s Sales
DAYBUE generated $140 million in net sales during the third quarter of fiscal 2026, out of $342 million in total revenue for Acadia. Those sales climbed 39% from a year earlier. Management said the increase came almost entirely from volume, meaning the company sold more of the drug rather than raising its price.
The main contributor to Acadia’s growth in the quarter was the uptake of DAYBUE STIX, a newer form of the drug on sale for about six months, management said. On that momentum, management raised its full-year 2026 guidance for DAYBUE net sales to a range of $505 million to $520 million. It also said it remains confident that DAYBUE can reach $700 million in sales by the end of 2028.
How Much Does Acadia Still Depend On NUPLAZID?
It depends on NUPLAZID more than on DAYBUE. NUPLAZID recorded $202 million in net sales during the third quarter, rising 12% from a year earlier on management’s adjusted basis.
A holder is therefore still exposed mainly to NUPLAZID. Acadia said on November 9, 2026, that a federal appeals court heard oral arguments in the appeal of a May 2025 court decision that upheld its patent on the NUPLAZID 34 mg capsule. The company said it continues to believe in the strength of its position.
DAYBUE’s own position is getting stronger. On the November 4 call, management said a newly allowed U.S. patent on DAYBUE’s dosing is expected to protect both forms of the drug through March 2041 once issued, a date that management said includes pediatric exclusivity. That would extend its patent protection by nearly five years. The drug also won European Commission approval in the quarter, and Acadia launched it in Germany in early October. Yet DAYBUE is still the smaller drug, so it cannot yet replace NUPLAZID’s sales.
A buyer also gets cash. At the end of September 2026, Acadia held $976 million in cash and short-term investments against $71.9 million of debt. That cash equals about $5.58 a share, compared with a $16.50 share price at the November 9 close, which was the lowest close in a year.
What Would Show DAYBUE’s Growth Slowing?
The first sign would be fewer new and returning patients starting DAYBUE STIX. More than half of all U.S. DAYBUE patients were already receiving STIX by the end of the third quarter, so the room left appears to lie mostly among patients new to the drug and those who stopped taking it.
Management said over 80% of the patients who had stopped are yet to retry DAYBUE in its STIX form. Among community doctors outside the centers of excellence, management put DAYBUE’s penetration at about 30%. Both figures represent management’s estimates of the room left, rather than sales already made.
Management expects to update its view of DAYBUE’s peak sales, likely in the first quarter of 2027. When Acadia next reports, expected in February 2027, DAYBUE’s quarterly net sales and the share of U.S. patients on STIX will be the figures to watch.
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