Definium Therapeutics, Inc. ("Definium" or the "Company"), 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 issuance of inducement grants to four newly hired non-executive employees consisting of (i) options to purchase an aggregate of 134,540 common shares of the Company (the "Options") and (ii) 34,500 performance share units (the "PSUs") (assuming achievement at target levels of performance) that, if earned, will be settled in Definium common shares upon vesting, with effective grant dates of February 24, 2026, February 27, 2026 and March 9, 2026. The Options have an exercise price equal to the closing price of Definium's common shares on the date of the respective grant, and will vest over a four-year period with 25% vesting on the first anniversary of the date of the grant and the remaining 75% vesting in substantially equal monthly increments over the three-year period thereafter, subject to each employee's continued employment. The PSUs will vest on the third anniversary of the grant date, subject to continued service through the vesting date. Actual earned PSUs can range from 0%-200% of the target number of PSUs and will be based on the achievement of certain performance metrics as measured at the end of the three-year performance period.

The Options and PSUs were granted as a material inducement to each employee's employment and were approved by Definium's Compensation Committee on February 23, 2026, in accordance with Rule 5635(c)(4) of The NASDAQ Stock Market LLC. The Options were granted outside Definium's equity incentive plans

About Definium Therapeutics

The mission of Definium Therapeutics is to forge a new era of psychiatry by applying scientific rigor to psychedelics, with the goal of developing accessible treatments that unlock healing at scale. Guided by a recognition that patients deserve more than better, Definium is relentlessly advancing a new generation of therapeutics intended to address underlying causes of psychiatric and neurological disorders. By turning evidence into impact, Definium aims to change the trajectory of today's mental health care crisis and enable a healthier future. Headquartered in New York, Definium Therapeutics trades on Nasdaq under the symbol DFTX.

For more information, visit https://definiumtx.com/ and follow Definium Therapeutics on Instagram, LinkedIn and X.

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Gitanjali Jain

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ir@definiumtx.com

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Definium Therapeutics Announces New Employee Inducement Grants