Definium Therapeutics, Inc.

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 completed an underwritten public offering of 23,676,471 common shares at $34.00 per share, generating approximately $805 million in gross proceeds. The offering, which included the full exercise of the underwriters' option for additional shares, closed on June 25, 2026. Proceeds will fund research and development, preparation for potential commercialization of DT120 ODT, and general corporate purposes. The capital raise follows strong Phase 3 results from the EMERGE trial evaluating DT120, an orally disintegrating LSD d-tartrate tablet for major depressive disorder. Canaccord reduced its price target on Definium to $58 from $60 but maintained a Buy rating, updating its model to reflect the increased share count from the financing.

Definium Therapeutics announced positive topline results from its Emerge Phase 3 study of DT120 ODT 100 microgram for major depressive disorder. The trial met its primary endpoint with a statistically significant improvement in MADRS total score at Week 6, showing an LS mean change of -13.3 for DT120 ODT versus -5.2 for placebo, a difference of -8.1 points. Rapid activity was observed with a placebo-adjusted reduction of -14.2 points at Week 1, and durable effects with a -7.3-point reduction at Week 12. Following the update, Robert W. Baird analyst Christopher Chen raised the price target on Definium Therapeutics to $57 from $37 while maintaining an Outperform rating.

Definium Therapeutics shares surged 49.8% after the company announced positive top-line results from its phase III Emerge study of DT120 orally disintegrating tablet in adults with major depressive disorder. The study met its primary endpoint, showing an 8.1-point placebo-adjusted reduction in depressive symptoms at week 6 as measured by the MADRS scale, and all key secondary endpoints were also met. At week 1, patients receiving a single 100 µg dose showed a 14.2-point placebo-adjusted improvement, with benefits sustained through week 12. Response rates at week 6 were 35% for DT120 versus 7% for placebo, and remission rates were 24% versus 3%. The treatment was generally well tolerated, with 99% of adverse events mild to moderate and no serious safety concerns.