Sometimes the best way to get the market's attention is to have a bigger player write a really big check. That's exactly what happened Thursday when Eli Lilly and Co. (Eli Lilly (LLY)) agreed to buy AtaiBeckley Inc. (AtaiBeckley (ATAI)) for up to $3.8 billion, sending shares of other psychedelic-focused biotechs soaring.

GH Research PLC (GH Research (GHRS)) jumped more than 11% to $29.99, while Definium Therapeutics Inc. (Definium Therapeutics (DFTX)) initially rose before settling down about 1.3% at $45.06. The moves are a classic case of sympathy trading — when one company in a hot space gets acquired, investors start betting on who might be next.

AtaiBeckley is one of several companies trying to usher in a new era of psychedelic medicine, and Lilly's willingness to pay billions for it is a big vote of confidence in the space. Bloomberg was the first to report the deal.

GH001 Draws Comparisons With AtaiBeckley's Lead Drug Candidate

So why is GH Research getting so much love? It's all about the drugs. GH Research's lead candidate, GH001, is a formulation of mebufotenin administered via a proprietary inhalation device. That's similar to AtaiBeckley's lead asset, BPL-003, which is mebufotenin benzoate given intranasally. Both are being developed for treatment-resistant depression, and investors are betting that GH Research could be the next target or at least benefit from the renewed focus on the space.

Prior Data Supports Treatment-Resistant Depression Program

GH Research has been building its case. In March 2026, the company published results from its Phase 2b trial of GH001 in treatment-resistant depression in JAMA Psychiatry. A post-hoc analysis showed that the drug worked regardless of how many prior antidepressant treatments patients had failed, with Day 8 remission rates ranging from 53.9% to 63.6% across subgroups. That's the kind of data that gets people excited.

In May, GH Research completed enrollment in a Phase 1 pharmacology trial in the U.K., testing a proprietary aerosol delivery device for GH001 in healthy volunteers. Based on those results, the company selected doses for a global Phase 3 pivotal program in treatment-resistant depression. And in January, the FDA lifted a clinical hold on GH Research's Investigational New Drug Application for GH001 — a hold that had been in place since September 2023 due to insufficient information to assess risks. That's a big hurdle cleared.

Shorter Treatment Duration For BPL-003

One of the key advantages of AtaiBeckley's BPL-003, according to Bloomberg's report, is its short treatment duration. The psychedelic effects last only about one to two hours, compared with some experimental therapies — including one from Compass Pathways Plc (Compass Pathways (CMPS)) — that may require patient monitoring for up to eight hours. That's a huge practical difference for clinics and patients alike. Shorter sessions mean more patients can be treated, and the logistics are much simpler.

For now, the market is betting that the psychedelic revolution is real, and Lilly's checkbook is the strongest evidence yet.