Definium Therapeutics, Inc. Announces Closing of $805 Million Upsized Public Offering, Including Full Exercise of the Underwriters’ Option to Purchase Additional Shares

Definium Therapeutics, Inc. (Nasdaq: DFTX) (the “Company” or “Definium”), a late-stage clinical biopharmaceutical company developing a new generation of therapeutics intended to address underlying causes of psychiatric and neurological disorders, today announced the closing of its previously announced underwritten public offering of 23,676,471 common shares, without par value, which includes the exercise in full by the underwriters of their option to purchase 3,088,235 additional common shares, at a public offering price of $34.00 per common share. All of the shares were offered by Definium. The gross proceeds from this offering were $805 million, before deducting underwriting discounts, commissions, and other offering-related expenses.

Definium intends to use the net proceeds from this offering for the research and development of its product candidates, preparation activities for potential commercialization of DT120 ODT, if approved, and working capital and general corporate purposes.

J.P. Morgan, Jefferies, Leerink Partners, and BofA Securities acted as the joint lead bookrunners for the offering, and Evercore ISI and Stifel acted as bookrunners for the offering. Oppenheimer & Co. and LifeSci Capital acted as co-lead managers for the offering. The offering closed on June 25, 2026. No distribution under the offering occurred in Canada or to a person resident in Canada.