Osisko Development Reports First Quarter 2025 Results

Press Release

Montreal, Québec, May 6, 2025 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV) (“Osisko Development” or the “Company”) reports its financial and operating results for the three months ended March 31, 2025 (“Q1 2025”).

Q1 2025 HIGHLIGHTS

Operating, Financial and Corporate Updates:

• As of March 31, 2025, the Company had approximately $77.6 million in cash and cash equivalents. Approximately $35.7 million (US$25.0 million) was outstanding as of the end of Q1 2025 under the delayed draw term loan with National Bank of Canada, which matures on October 31, 2025.
• On January 9, 2025, the Company announced the appointment of Mr. David Rouleau as Vice President, Project Development of the Company, and the resignation of Mr. Éric Tremblay as Chief Operating Officer of the Company.
• On February 3, 2025, the Company released drilling results from its 2024 initial exploration and historic data validation infill drill campaign at its Quesnel River Mine Prospect located within the Company’s wider Cariboo Gold Project.
• On March 26, 2025, the Company appointed Philip Rabenok as Vice President, Investor Relations. Mr. Rabenok joined Osisko Development in November 2022 as Director, Investor Relations.

Cariboo Gold Project – British Columbia, Canada (100%-owned)

• 2025 Feasibility Study. On April 28, 2025, the Company released the results of its optimized feasibility study for the Cariboo Gold Project (“2025 FS”). The 2025 FS was prepared in accordance with NI 43-101 (as defined herein) by BBA Engineering Ltd. (“BBA”) as lead independent consultant, and supported by other independent engineering firms. The technical report in respect of the 2025 FS will be filed within 45 days of April 28, 2025.
  • The 2025 FS outlines strong base case economics with after-tax NPV5% of $943 million, and unlevered after-tax IRR of 22.1% at a US$2,400/oz gold price assumption. It outlines average annual gold production of 190,000 ounces of gold over a 10-year mine life (202,000 ounces per year in the first five years), producing a total of 1.89 million ounces (payable) over the life-of-mine with average AISC² of US$1,157 per ounce. Key summary results and assumptions are outlined below in Table 1:

1. Payback is calculated from commercial production, which is defined as the achievement of reaching a minimum of 30 consecutive days of operations during which the mill operated at an average of 60% of nameplate throughput of 4,900 tpd.
2. All-in sustaining costs per ounce (“AISC”) and free cash flow are non-IFRS measures or ratios. Refer to “Non-IFRS Financial Measures” at the end of this news release for more information.
3. Spot case is based on the LBMA gold price as of the close of business on April 23, 2025, rounded to nearest $100/oz and the USDCAD exchange rate is based on the Bank of Canada daily exchange rate, rounded to nearest five cents.
   • The Cariboo Gold Project is envisioned as a low-impact underground operation using mechanized bulk mining methods, with attractive operating costs, manageable capital requirements, and is well-positioned to benefit from favorable macroeconomic and gold price trends. Additionally, the planned processing plant and surface infrastructure design have been strategically optimized to accommodate potential future expansion options. Initial capital costs for the Cariboo Gold Project are estimated at $881 million, with sustaining capital costs of $525 million (life-of-mine).
   • The 2025 FS incorporated several important improvements and de-risking initiatives that better position the Cariboo Gold Project from an execution, financing, and operational perspective. For additional details on the results, assumptions, qualifications and limitations of the 2025 FS, refer to the full text of the 2025 FS News Release (as defined herein) dated April 28, 2025.
   • See “Technical Reports” for cautionary language in respect of the assumptions, parameters, qualifications, limitations and methods used in preparing the 2025 FS.

• Project Financing. The Company is actively engaged in ongoing discussions on various funding options, including a comprehensive project construction financing package, for the development of the Cariboo Gold Project.
  • A formal positive final investment decision, along with securing of a project financing package in the coming months, would enable certain construction activities to commence in the second half of 2025, with project completion targeted for the end of 2027.
  • Subsequent to the granting of the Mines Act (British Columbia) and Environmental Management Act (British Columbia) permits in the fourth quarter of 2024, work is ongoing with the Ministry of Water, Land and Resource Stewardship and the Ministry of Forests on obtaining all necessary approvals for the construction of the transmission line, expected in H2 2025.
• Pre-Construction Activities. During the first quarter of 2024, under an existing provincial permit, the Company commenced an underground development drift from the existing Cow Portal into the Cariboo Gold Project’s Lowhee Zone to extract a bulk sample of up to 10,000 tonnes of mineralized material.
  • 100% of the underground development has been successfully completed, totalling approximately 1,172 m, to access the target area.
  • The extraction, sampling, assaying, and analysis of mineralized material from the target zone is progressing. To date, approximately 7,400 tonnes of material have been extracted, with additional targeted sampling contemplated to complete the 10,000-tonne program. Completion of the program has been extended into the third quarter of 2025 due to lengthy timeframes for receiving assay results and analyzing the data, as well as challenges in sourcing and securing a suitable processing facility to produce gold doré. Once all information is available, a reconciliation process will be undertaken to compare the bulk sample results with the predicted tonnes and grade.

Tintic Project – Utah, U.S.A. (100%-owned)

• Phase II Regional Drilling. As part of the ongoing Phase II regional drilling program initiated in December 2024, the Company is progressing toward the completion of two drill holes at the Big Hill West and Zuma porphyry targets, which are expected to be completed in the coming months.
• During the quarter, a small-scale heap leach project was undertaken to re-treat certain tailings and stockpile material, with modest gold ounce production expected to begin in the second quarter of 2025. Management continues to evaluate options for the next steps at the Tintic Project.

San Antonio Gold Project – Sonora State, Mexico (100%-owned)

• The San Antonio Gold Project remains in care and maintenance and the Board of Directors of the Company has authorized a strategic review. The approval process for mining permits appears to be gaining traction, specifically for open-pit mining in the country, and the Company intends to re-submit its two permit applications this year.

KEY UPCOMING MILESTONES

*as at March 31, 2025

Notes:

1. The expenditures disclosed in this table include amounts approved by the Board of Directors up until the end of June 2025. Additional expenditures will be required to complete certain of the milestones and are subject to approval by the Board of Directors.

SUBSEQUENT TO Q1 2025

• Effective at the opening of markets on April 17, 2025, the Company’s common share purchase warrants issued pursuant to private placements completed between October and November 2024 were listed for trading on the TSX Venture Exchange under the symbol “ODV.WT.V.”.

Consolidated Financial Statements

The Company’s unaudited condensed interim consolidated financial statements (the “Financial Statements”) and related management’s discussion and analysis (“MD&A”) for the three months ended March 31, 2025 have been filed with Canadian securities regulatory authorities and the U.S. Securities and Exchange Commission. These filings are available on the Company’s website at www.osiskodev.com, on SEDAR+ (www.sedarplus.ca) and on EDGAR (www.sec.gov) under Osisko Development’s issuer profile.

Qualified Persons

The scientific and technical information contained in this news release has been reviewed and approved by Victor Gauthier, P.Eng., Manager – Technical Services of Osisko Development, and Eryn Doyle, P.Geo., Senior Exploration Manager of Osisko Development, each of whom is considered to be a “qualified person” within the meaning of National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”).

Technical Reports

Information relating to the Cariboo Gold Project and the 2025 FS on the Cariboo Gold Project is supported by the news release disseminated by the Company on April 28, 2025 (titled “Osisko Development Announces Optimized Feasibility Study for Permitted Cariboo Gold Project with C$943 Million After-Tax NPV5% and 22.1% IRR at US$2,400 / oz Base Case Gold Price; At US$3,300 / oz Spot Gold C$2.1 Billion After-Tax NPV5% and 38.0% IRR”) (the “2025 FS News Release”). The 2025 FS will be supported by a technical report being prepared in accordance with NI 43-101 with an effective date of April 22, 2025. The Company intends to file such technical report in respect of the 2025 FS (the “Cariboo Technical Report”) on SEDAR+ (www.sedarplus.ca) and on EDGAR (www.sec.gov) under Osisko Development’s issuer profile within 45 days of April 28, 2025 (being the date of the 2025 FS News Release). When filed, the Cariboo Technical Report will supersede the existing technical report on the Cariboo Gold Project titled “Feasibility Study for the Cariboo Gold Project, District of Well, British Columbia, Canada”, dated January 10, 2023 (amended January 12, 2023) with an effective date of December 30, 2022 (the “2023 Technical Report”).

Readers are cautioned that there are material changes to scientific and technical information since the 2023 Technical Report as outlined in the 2025 FS News Release. The key assumptions, parameters, qualifications, limitations and methods used in the 2025 FS, certain of which are described in the 2025 FS News Release, will be further described in the Cariboo Technical Report.

Information relating to the Tintic Project and the current mineral resource estimate for the Trixie deposit (the “2024 Trixie MRE”) is supported by the technical report titled “NI 43-101 Technical Report, Mineral Resource Estimate for the Trixie Deposit, Tintic Project, Utah, United States of America” dated April 25, 2024 (with an effective date of March 14, 2024) (the “Tintic Technical Report”).

Information relating to San Antonio Gold Project is supported by the technical report titled “NI 43-101 Technical Report for the 2022 Mineral Resource Estimate on the San Antonio Project, Sonora, Mexico”, dated July 12, 2022 (with an effective date of June 24, 2022) (the “San Antonio Technical Report”, and collectively, with the Tintic Technical Report, 2023 Technical Report and the Cariboo Technical Report, the “Technical Reports”).

For readers to fully understand the information in the Technical Reports, reference should be made to the full text of the Technical Reports in their entirety, including all assumptions, parameters, qualifications, limitations and methods therein. The Technical Reports are intended to be read as a whole, and sections should not be read or relied upon out of context. The Technical Reports were, or will be, prepared in accordance with NI 43-101 and are, or will be, available electronically on SEDAR+ (www.sedarplus.ca) and on EDGAR (www.sec.gov) under Osisko Development’s issuer profile and on the Company’s website at www.osiskodev.com.

End Notes (excluding tables)

1. In this news release the Company uses certain abbreviations, including: net present value (“NPV”); NPV at a 5% discount rate (“NPV5%”); internal rate of return (“IRR”); per ounce (“/oz”); all-in sustaining costs (“AISC”).
2. All-in sustaining costs per ounce and free cash flow are non-IFRS measures or ratios. Refer to “Non-IFRS Financial Measures” at the end of this news release for more information.

ABOUT OSISKO DEVELOPMENT CORP.

Osisko Development Corp. is a 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%-owned Cariboo Gold Project, located in central B.C., Canada. Its project pipeline is complemented by the Tintic Project in the historic East Tintic mining district in Utah, U.S.A., 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.

For further information, visit our website at www.osiskodev.com or contact:

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