Osisko Development increases financing to $60-million

Mr. Sean Roosen reports OSISKO DEVELOPMENT ANNOUNCES UPSIZING OF PREVIOUSLY ANNOUNCED "BOUGHT DEAL" LIFE OFFERING; ADDITIONAL CONCURRENT PRIVATE PLACEMENT As a result of excess demand, Osisko Development Corp. has entered into an amending agreement with National Bank Financial Inc., BMO Capital Markets and RBC Capital Markets, acting as co-lead underwriters and co-bookrunners, to increase the size of its previously announced bought deal financing to $60-million. LIFE (listed issuer financing exemption) offering As a result of the amendment, Osisko Development will now issue three tranches of shares pursuant to the listed issuer financing exemption (as defined herein) for aggregate gross proceeds of $49,999,980 as follows: National flow-through shares: 2.99 million common shares of the company that will qualify as flow-through shares within the meaning of Subsection 66(15) of the Income Tax Act (Canada) at a price of $6.69 per flow-through share for gross proceeds of $20,003,100; British Columbia flow-through shares: 1,444,000 common shares of the company to certain eligible British Columbia resident subscribers that will qualify as flow-through shares within the meaning of Subsection 66(15) of the tax act at a price of $6.93 per British Columbia flow-through share for gross proceeds of $10,006,920; Common shares: 4,182,000 common shares of the company at a price of $4.78 per common share for gross proceeds of $19,989,960. Concurrent private placement As a result of the amendment, Osisko Development will also complete a concurrent bought deal private placement of 2,092,100 common shares at a price of $4.78 per common share for gross proceeds of $10,000,238. The company intends to use the net proceeds of the common shares issued pursuant to the LIFE offering and concurrent private placement, being approximately $30-million, to contribute to the capital required to construct the Cariboo gold project and related preconstruction activities. In all other respects, the terms of the LIFE offering, including the use of proceeds of the flow-through shares, will remain as previously disclosed in the original news release of the company dated Oct. 8, 2025. Closing of the LIFE offering and the concurrent private placement are expected to occur on the same date, being on or about Oct. 29, 2025, 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. Notwithstanding the foregoing, the closing date must occur no later than the 45th day following the date of the launch release on Oct. 8, 2025. The LIFE offering will be made pursuant to the listed issuer financing exemption available under Part 5A of National Instrument 45-106, Prospectus Exemptions, as amended by Coordinated Blanket Order 45-935, Exemptions from Certain Conditions of the Listed Issuer Financing Exemption, in each of the provinces and territories of Canada. The common shares under the LIFE offering may also be offered and the flow-through shares may also be offered (or reoffered) in such offshore jurisdictions as may be agreed to by the company and the underwriters pursuant to available prospectus or registration exemptions in accordance with applicable laws provided that no prospectus filing or comparable obligation arises in connection with the sale of the common shares or the flow-through shares in such other jurisdiction. The common shares and the flow-through shares issued under the listed issuer financing exemption will not be subject to a statutory hold period pursuant to applicable Canadian securities laws. The concurrent private placement will be conducted on a private placement basis pursuant to available exemptions under NI 45-106, other than the listed issuer financing exemption, in each of the provinces and territories of Canada and in such offshore jurisdictions as may be agreed to by the company and the underwriters pursuant to available prospectus or registration exemptions in accordance with applicable laws provided that no prospectus filing or comparable obligation arises in connection with the sale of the common shares in such other jurisdiction. 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. An amended and restated offering document relating to the LIFE offering will be available to be accessed on SEDAR+ under Osisko Development's issuer profile and on the company's website. Prospective investors should read the offering document before making an investment decision. About Osisko Development Corp. Osisko Development is a continental North American gold development company focused on past-producing mining camps located in mining-friendly jurisdictions with district-scale potential. The company's objective is to become an intermediate gold producer by advancing its flagship permitted 100-per-cent-owned Cariboo gold project, located in central British Columbia, Canada. Its project pipeline is complemented by the Tintic project in the historic East Tintic mining district in Utah, United States, and the San Antonio gold project in Sonora, Mexico -- brownfield properties with significant exploration potential, extensive historical mining data, access to existing infrastructure and skilled labour. The company's strategy is to develop attractive, long-life, socially and environmentally responsible mining assets while minimizing exposure to development risk and growing mineral resources. We seek Safe Harbor.