Definium Therapeutics, Inc.Positive Phase 3 data for LSD-based depression therapy de-risks program and drives stock surge.

Definium Therapeutics, a clinical-stage biopharmaceutical company, saw its shares more than double during the second quarter of 2026 after reporting positive topline results from its pivotal Phase 3 study in major depressive disorder. The Meridian Small Cap Growth Fund, managed by ArrowMark Partners, highlighted the company in its Q2 2026 investor letter, noting that the trial comfortably exceeded the efficacy bar and showed durable treatment effects with high remission rates versus placebo. Definium is developing a rapid-acting, single-dose LSD-based therapy for major depressive disorder and generalized anxiety disorder, administered in a monitored clinical setting. The fund stated that the readout meaningfully de-risked the program and set up the first generalized-anxiety-disorder readout, expected shortly, as the next potential catalyst. As of July 29, 2026, Definium Therapeutics closed at $42.16 per share with a market capitalization of $5.6 billion, and its shares had gained 363.81% over the past 52 weeks.
Definium Therapeutics, Inc.Positive Phase 3 data for LSD-based depression therapy de-risks program and drives stock surge.