Osisko Development Announces Further Upsize of Previously Announced "Bought Deal" Offering

Total Upsized Offering of C$75 Million

NOT FOR DISTRIBUTION TO UNITED STATES NEWS WIRE SERVICES OR FOR DISSEMINATION IN THE UNITED STATES

MONTREAL, Oct. 15, 2025 (GLOBE NEWSWIRE) -- Osisko Development Corp. (NYSE: ODV, TSXV: ODV) ("Osisko Development" or the "Company") is pleased to announce that, as a result of excess demand, it has entered into a further amending agreement (the "Amendment") with National Bank Financial Inc., BMO Capital Markets and RBC Capital Markets, acting as co-lead underwriters and co-bookrunners (collectively, the "Underwriters"), to increase the size of its previously announced "bought deal" financing from C$60 million to C$75 million (the "Offering").

As announced by the Company on October 9, 2025 (see news release entitled "Osisko Development Announces Upsizing of Previously Announced "Bought Deal" LIFE Offering; Additional Concurrent Private Placement"), Osisko Development has agreed to issue (i) three tranches of shares under the "listed issuer financing exemption" available under Part 5A of National Instrument 45-106 – Prospectus Exemptions ("NI 45-106"), as amended by Coordinated Blanket Order 45-935 – Exemptions from Certain Conditions of the Listed Issuer Financing Exemption (the "LIFE Exemption") in each of the provinces and territories of Canada, comprising national flow-through shares, British Columbia flow-through shares and common shares of the Company ("Common Shares"), for gross proceeds of approximately C$50 million, and (ii) additional Common Shares on a private placement basis pursuant to exemptions available under NI 45-106, other than the LIFE Exemption, for gross proceeds of approximately C$10 million (the "Concurrent Private Placement").

Pursuant to the Amendment, the Company has agreed to increase the size of the Concurrent Private Placement by approximately C$15 million, such that after giving effect to the Amendment, the Concurrent Private Placement will consist of an aggregate of 5,230,200 Common Shares at a price of C$4.78 per Common Share for gross proceeds of C$25,000,356. Other than the increase in the size of the Concurrent Private Placement, all other terms of the Offering remain unchanged following the Amendment.

Closing of the LIFE Offering and the Concurrent Private Placement are expected to occur on the same date, being on or about October 29, 2025 (the "Closing Date"), and remain subject to certain conditions including, but not limited to, the receipt of all necessary regulatory approvals, including the conditional approval of the TSX Venture Exchange and the New York Stock Exchange. The Common Shares issued under the Concurrent Private Placement will be subject to a statutory hold period of four months and one day pursuant to applicable Canadian securities laws.