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Gradient REVIVING HISTORIC MINING CAMPS IN NORTH AMERICA AUGUST 2025 ODV NYSE TSXV | osiskodev.com INVESTOR PRESENTATION
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Gradient ODV NYSE TSXV osiskodev.com CAUTIONARY STATEMENTS 2 CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING INFORMATION Certain statements contained in this presentation (this "Presentation") may be deemed "forward-looking statements" within the meaning of the United States Private Securities Litigation Reform Act of 1995 and "forward-looking information" within the meaning of applicable Canadian securities legislation (together, "forward-looking statements"). These forward-looking statements, by their nature, require Osisko Development Corp. ("Osisko Development" or the "Company") to make certain assumptions and necessarily involve known and unknown risks and uncertainties that could cause actual results to differ materially from those expressed or implied in these forward-looking statements. Forward- looking statements are not guarantees of performance. Words such as "may", "will", "would", "could", "expect", "believe", "plan", "anticipate", "intend", "estimate", "continue", or the negative or comparable terminology, as well as terms usually used in the future and the conditional, are intended to identify forward-looking statements. Information contained in forward-looking statements is based upon certain material assumptions that were applied in drawing a conclusion or making a forecast or projection, including the assumptions, qualifications and limitations relating to an optimized feasibility study for the Cariboo Gold Project (the "2025 Cariboo FS") (including, but not limited to, the mineral resources, mineral reserves, production profile, mine design and project economics); the Company being construction and operation ready and the timing for the commencement of construction activities; the ability and timing of the Company to deliver any additional optimization opportunities; the ability and timing of the Company to reach a formal positive final investment decision in respect of the Cariboo Gold Project; the ability and timing of the Company to secure a project financing package to fund construction activities at the Cariboo Gold Project and the terms of such financing; the ability and timing of the Company to commence and complete detailed engineering / procurement, underground development, construction and ramp-up and first gold pour; the impact and potential of the Cariboo Gold Project on shareholders, Indigenous nations and other stakeholders; the ability to successfully engage and collaborate with stakeholders, including reaching agreements with the Xatśūll First Nation; any meaningful re-rate potential through project financing, construction and production phrases (if at all); Cariboo Gold Project being a scalable project; Cariboo Gold Project being well-positioned among the top underground gold asset in Canada with strong upside potential in the long run; Cariboo Gold Project being well-situated relative to other Canadian underground operations in total cash costs and all-sustaining costs; sustainability and environmental impacts of operations at the Company's properties; progress in respect of pre-construction activities at Cariboo Gold Project including bulk sample and underground development work; mineral resource category conversion; the timing and status of any additional required permits or amendments thereto, or other regulatory approval requirements; the future development and operations at the Cariboo Gold Project; the results of ongoing stakeholder engagement; the capital resources available to the Company; the ability of the Company to execute its planned activities, including as a result of its ability to seek additional funding; management's perceptions of historical trends, current conditions and expected future developments; the ability and timing for Cariboo Gold Project to reach commercial production (if at all); the expected cash flow (and underlying assumptions) in respect of the Cariboo Gold Project; the significance of the high-priority target drilling; the utility of modern exploration techniques; the potential for parallel high-grade gold fissure zones at Trixie; the potential of Tintic to host a copper-gold porphyry center; the potential for unknown mineralized structures to extend existing zones of mineralization; the utility and significance of historic data, including the significance of the district hosting past producing mines; future mining activities; the potential of high grade gold mineralization on Trixie and Cariboo Gold Project; the ability to generate additional drill targets; the ability of management to understand the geology and potential of the Company's properties; continuation of test mining activities at Trixie (if at all); the ongoing advancement of the deposits on the Company's properties; the deposit remaining open for expansion at depth and down plunge; the ability to realize upon any mineralization in a manner that is economic; the ability and timing for the permitting at San Antonio; the impact of permitting delays at San Antonio; the outcome of the strategic review of the San Antonio Project; sustainability and environmental impacts of operations at the Company's properties; the results (if any) of further exploration work to define and expand mineral resources; the ability of exploration work (including drilling) to accurately predict mineralization; the ability of the Company to expand mineral resources beyond current mineral resource estimates and to convert some or all of these mineral resources to mineral reserves; the ability for the Company to expand throughput or increase production at the Cariboo Gold Project; the ability of the Company to discover additional deposits within the Cariboo Gold Project area; the ability of the Company to complete its exploration and development objectives for its projects in the timing contemplated and within expected costs (if at all); the ability to derisk the Cariboo Gold Project towards final investment decision; the ability to adapt to changes in gold prices, estimates of costs, estimates of planned exploration and development expenditures; the ability of the Company to obtain further capital on reasonable terms; the profitability (if at all) of the Company's operations; the availability of additional optimization opportunities at the Cariboo Gold Project and the impact thereof on project economics; as well as other considerations that are believed to be appropriate in the circumstances, and any other information herein that is not a historical fact may be "forward looking information". Material assumptions also include, assumptions and qualifications underlying the 2025 Cariboo FS, management's perceptions of historical trends, management's understanding of the permitting process and status thereof, the ability of exploration (including drilling and chip sampling assays, and face sampling) to accurately predict mineralization; budget constraints and access to capital on terms acceptable to the Company, current conditions and expected future developments, regulatory framework remaining defined and understood, results of further exploration work to define or expand any mineral resources, gold prices, the costs required to advance the Cariboo Gold Project to construction, the results of the 2025 Cariboo FS as an indicator of quality and robustness of the Cariboo Gold Project, as well as other considerations that are believed to be appropriate in the circumstances. Osisko Development considers its assumptions to be reasonable based on information currently available, but cautions the reader that their assumptions regarding future events, many of which are beyond the control of Osisko Development, may ultimately prove to be incorrect since they are subject to risks and uncertainties that affect Osisko Development and its business. Such risks and uncertainties include, among others, risks relating to third-party approvals, including the issuance of permits by the government, capital market conditions and the Company's ability to access capital on terms acceptable to the Company for the contemplated exploration and development at the Company's properties; the ability to continue current operations and exploration; regulatory framework and presence of laws and regulations that may impose restrictions on mining; the ability of exploration activities (including drill results and chip sampling, and face sampling results) to accurately predict mineralization; errors in management's geological modelling; the timing and ability of the Company to obtain and maintain required approvals and permits; the results of exploration activities; risks relating to exploration, development and mining activities; the global economic climate; metal and commodity prices; fluctuations in the currency markets; dilution; environmental risks; and community, non-governmental and governmental actions and the impact of stakeholder actions. Readers are urged to consult the disclosure provided under the heading "Risk Factors" in the Company's annual information form for the year ended December 31, 2024 as well as the financial statements and MD&A for the year ended December 31, 2024 and the period ended June 30, 2025, which have been filed on SEDAR+ (www.sedarplus.ca) under Osisko Development's issuer profile and on the SEC's EDGAR website (www.sec.gov), for further information regarding the risks and other factors facing the Company, its business and operations. Although the Company believes the expectations conveyed by the forward-looking statements are reasonable based on information available as of the date hereof, no assurances can be given as to future results, levels of activity and achievements. The Company disclaims any obligation to update any forward-looking statements, whether as a result of new information, future events or results or otherwise, except as required by law. Forward-looking statements are not guarantees of performance and there can be no assurance that these forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements. Unless otherwise noted, this Presentation has been prepared based on information available as of August 15, 2025. All currency references are to Canadian dollars, unless specified otherwise. NON-IFRS MEASURES Osisko Development used in this Presentation, certain non-IFRS measures including, "all-in sustaining cost" or "AISC" and "total cash cost" and "free cash flow". All-in sustaining cost per gold ounce is defined as production costs less silver sales plus general and administrative, exploration, other expenses and sustaining capital expenditures divided by gold ounces. Cash costs are a non-IFRS measure reported by ODV on an ounces of gold sold basis. Cash costs include mining, processing, refining, general and administration costs and royalties but excludes depreciation, reclamation, income taxes, capital and exploration costs for the life of the mine. Free cash flow is calculated as cash flow from mine-site operating activities less capital expenditures. The Company believes that such measures provide investors with an alternative view to evaluate the performance of the Company. Non-IFRS measures do not have any standardized meaning prescribed under International Financial Reporting Standards ("IFRS"). Therefore, they may not be comparable to similar measures employed by other companies. The data is intended to provide additional information and should not be considered in isolation or as a substitute for measures of performance prepared in accordance with IFRS. CAUTIONARY NOTE TO U.S. INVESTORS The Company is subject to the reporting requirements of the applicable Canadian securities laws and, as a result, reports information regarding mineral properties, mineralization and estimates of mineral reserves and mineral resources, including the information in its technical reports, financial statements, MD&A and this Presentation, in accordance with Canadian reporting requirements, which are governed by NI 43-101 (as defined below). As such, such information concerning mineral properties, mineralization and estimates of mineral reserves and mineral resources, including the information in its technical reports, financial statements, MD&A and this Presentation, is not comparable to similar information made public by U.S. companies subject to the reporting and disclosure requirements of the U.S. Securities and Exchange Commission ("SEC"). Further to recent amendments, U.S. mineral property disclosure requirements (the "SEC Rules") are now governed by subpart 1300 of Regulation S-K under the U.S. Securities Act. Under the SEC Rules, the SEC now recognizes estimates of "measured mineral resources", "indicated mineral resources" and "inferred mineral resources." In addition, the SEC has amended its definitions of "proven mineral reserves" and "probable mineral reserves" to be "substantially similar" to the corresponding standards adopted by the Canadian Institute of Mining, Metallurgy and Petroleum, adopted by the CIM Council ("CIM Standards"), which is the required definition standard adopted by NI 43-101. While the SEC will now recognize "measured mineral resources", "indicated mineral resources" and "inferred mineral resources", U.S. investors should not assume that any part or all of the mineralization in these categories will ever be converted into a higher category of mineral resources or into mineral reserves. Mineralization described using these terms has a greater amount of uncertainty as to its existence and feasibility than mineralization that has been characterized as reserves. Accordingly, U.S. investors are cautioned not to assume that any measured mineral resources, indicated mineral resources, or inferred mineral resources that the Company reports are or will be economically or legally mineable. Further, "inferred mineral resources" have a greater amount of uncertainty as to their existence and as to whether they can be mined legally or economically. Therefore, U.S. investors are also cautioned not to assume that all or any part of the "inferred mineral resources" exist. Under Canadian securities laws, estimates of "inferred mineral resources" may not form the basis of feasibility or pre- feasibility studies, except in rare cases. While the above terms are "substantially similar" to CIM Standards, there are differences in the definitions under the SEC Rules and the CIM Standards. Accordingly, there is no assurance any mineral reserves or mineral resources that the Company may report as "proven mineral reserves", "probable mineral reserves", "measured mineral resources", "indicated mineral resources" and "inferred mineral resources" under NI 43-101 would be the same had the Company prepared the reserve or resource estimates under the SEC Rules.
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Gradient ODV NYSE TSXV osiskodev.com CAUTIONARY STATEMENTS 3 CAUTION REGARDING MINERAL RESOURCE ESTIMATES This Presentation uses the terms measured, indicated and inferred mineral resources as a relative measure of the level of confidence in the mineral resource estimate. Readers are cautioned that mineral resources are not mineral reserves and that the economic viability of resources that are not mineral reserves has not been demonstrated. The mineral resource estimate disclosed in this Presentation may be materially affected by geology, environmental, permitting, legal, title, socio-political, marketing or other relevant issues. Mineral Resources are reported using the 2014 CIM Definition Standards and were estimated in accordance with the CIM 2019 Best Practices Guidelines, as required by NI 43- 101. Under NI 43-101, estimates of inferred mineral resources may not form the basis of feasibility or pre-feasibility studies or economic studies except for preliminary economic assessments. Readers are cautioned not to assume that further work on the stated mineral resources will lead to mineral reserves that can be mined economically. CAUTION REGARDING TEST MINING WITHOUT FEASIBILITY STUDY The Company cautions that its prior decision to commence small-scale underground mining activities and batch vat leaching at the Trixie test mine was made without the benefit of a feasibility study, or reported mineral resources or mineral reserves, demonstrating economic and technical viability, and, as a result there may be increased uncertainty of achieving any particular level of recovery of material or the cost of such recovery. The Company cautions that historically, such projects have a much higher risk of economic and technical failure. Small scale test-mining at Trixie was suspended in December 2022, resumed in the second quarter of 2023, and suspended once again in December 2023. If and when small-scale test-mining recommences at Trixie, there is no guarantee that production will continue as anticipated or at all or that anticipated production costs will be achieved. The failure to continue production may have a material adverse impact on the Company's ability to generate revenue and cash flow to fund operations. Failure to achieve the anticipated production costs may have a material adverse impact on the Company's cash flow and potential profitability. In continuing operations at Trixie after closing, the Company has not based its decision to continue such operations on a feasibility study, or reported mineral resources or mineral reserves demonstrating economic and technical viability. BURGIN HISTORIC RESOURCE The past producing Burgin mine, previously operated by Kennecott until 1978, has potential for a significant silver-lead-zinc-gold deposit. The historic resource as outlined in the technical report entitled "Technical Report on the Burgin Extension Deposit – Preliminary Economic Assessment, Burgin Project, East Tintic Mining District, Utah County, Utah, USA" dated December 2, 2011 (effective date November 17, 2011) which was prepared for Andover Ventures Inc. and Chief Consolidated Mining Co. by Paul G. Tietz, C.P.G., Neil Prenn, PE, Jeffery Wood, PE and Thomas Gast which had been prepared in compliance with NI 43-101 at the time it was published (the "2011 PEA"). The Burgin historical estimates are qualified entirely by the assumptions, qualifications and parameters outlined in the full text of the 2011 PEA, a copy of which is accessible on SEDAR+ under Andover Mining Corp.'s issuer profile. Osisko Development believes that the historic resource continues to be relevant and reliable as an indication of the potential of the Burgin Mine. Further exploration work including drilling will be required to upgrade the historic resource to current. Osisko Development cautions sufficient work has not been done to classify the historic resources as a current resource and Osisko Development is not treating the historic resources as a current resource. SCIENTIFIC AND TECHNICAL INFORMATION Scientific and technical information relating to the Cariboo Gold Project and the 2025 Cariboo FS is supported by the technical report titled "NI 43-101 Technical Report, Feasibility Study for the Cariboo Gold Project, District of Wells, British Columbia, Canada" and dated June 11, 2025 (with an effective date of April 25, 2025) (the "Cariboo Technical Report"). The Cariboo Technical Report supersedes the technical report titled "NI 43-101 Technical Report, Feasibility Study for the Cariboo Gold Project, District of Wells, British Columbia" (as amended) dated January 12, 2023 (with an effective date of December 30, 2022), which should no longer be replied upon. Scientific and technical information relating to the Tintic Project and the updated mineral resource estimate for the Trixie deposit (the "2024 Trixie MRE"), and the assumptions, qualifications and limitations thereof, 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" and dated April 25, 2024 (with an effective date of March 14, 2024), prepared for the Company by independent representatives of Micon International Limited, being William Lewis, P. Geo, and Alan J. San Martin, MAusIMM(CP) (the "Tintic Technical Report"). The 2024 Trixie MRE supersedes the technical report titled "NI 43-101 Technical Report, Initial Mineral Resource Estimate for the Trixie Deposit, Tintic Project, Utah, United States of America" dated January 27, 2023 (with an effective date of January 10, 2023) (the "2023 Trixie MRE"). The scientific and technical information relating to the San Antonio Project is supported by the technical report entitled "NI 43-101 Technical Report for the 2022 Mineral Resource Estimate on the San Antonio Project, Sonora, Mexico" and dated July 12, 2022 (with an effective date of June 24, 2022) prepared for Osisko Development by Micon International Limited (the "San Antonio Technical Report", and collectively, with the Tintic Technical Report, 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 prepared in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101") and is 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. QUALIFIED PERSONS Victor Gauthier, P.Eng., Manager – Technical Services and Eryn Doyle, P.Geo., Senior Exploration Manager each of Osisko Development Corp., are considered a "qualified person" within the meaning of NI 43-101 and have reviewed and approved the scientific and technical information contained herein. ABBREVIATIONS AND UNITS OF MEASUREMENT In this Presentation, the Company uses certain abbreviations, including: measured and indicated ("M&I"), million ("M"), thousand ("k"), metric tonnes ("t"), troy ounces ("oz"), grams per tonne ("g/t"), gold ("Au"), silver ("Ag"), copper ("Cu"), lead ("Pb"), zinc ("Zn"), net present value ("NPV"); NPV at a 5% discount rate ("NPV5%"); internal rate of return ("IRR"); measured and indicated ("M&I"); million ("m"); thousand ("k"); metric tonne ("t"); troy ounce ("oz"); grams per tonne ("g/t"); gold ("Au"); silver ("Ag"); life of mine ("LOM"); tonnes per day ("tpd"); free cash flow ("FCF"); years ("yrs"); per annum ("pa"); average ("avg."); life-of-mine ("LOM"); versus ("vs."). ACCURACY AND RELIABILITY OF THIRD PARTY INFORMATION Certain information contained herein is based on, or derived from, information provided by independent third-party sources. ODV believes that such information is accurate and that the sources from which it has been obtained are reliable, however, ODV has not independently verified such information and does not assume any responsibility for the accuracy or completeness of such information.
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Gradient ODV NYSE TSXV osiskodev.com INVESTMENT HIGHLIGHTS Building Toward Becoming a Premier North American Mid-tier Gold Mining Company 4 1. Based on the Investment Attractive Index as outlined in the Fraser Institute Annual Survey of Mining Companies (2024). 2. https://www.mining.com/featured-article/ranked-worlds-top-20-largest-gold-mines ADVANCING SHOVEL READY CARIBOO GOLD PROJECT IN CANADA Limited universe of permitted development stage gold assets of scale in Tier 1 jurisdictions1 FOCUS ON SCALABLE ASSETS WITH DISTRICT SCALE POTENTIAL Multi-million-ounce deposit in the underexplored Cariboo gold belt; Developing the historic Tintic Project in Utah, USA with prospective gold, Cu-Au-Mo porphyry, epithermal and CRD targets EXPERIENCED TEAM LED BY CEO SEAN ROOSEN Led the successful discovery, development, and operation of the Canadian Malartic gold mine— consistently ranked among the largest operating gold mines globally2 RESPONSIBLE STAKEHOLDER ENGAGEMENT Focused on fostering and developing long-term partnerships and positive stakeholder relations including with principal First Nations partners and host communities
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Gradient ODV NYSE TSXV osiskodev.com © GeoNames, Microsoft, OpenStreetMap, TomTom Powered by Bing MINING FRIENDLY JURISDICTIONS 5 1. Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. Mineral reserves include probable reserves 2.071 Moz Au (17.815 Mt grading 3.62 g/t Au). Mineral resources include in the measured category, 8 koz Au (47 kt grading 5.06 g/t Au); in Indicated, 1.604 Moz Au (17.332 Mt grading 2.88 g/t Au); in Inferred, 1.864 Moz Au (18.774 Mt grading 3.09 g/t Au). M&I resources are exclusive of mineral reserves. 2. Refer to the full text of the Tintic Technical Report for the assumptions, qualifications and limitations relating to disclosure on the 2024 Trixie MRE. M&I resources consist of: (i) measured mineral resources (120 kt grading 27.36 g/t Au and 61.73 g/t Ag); and (ii) indicated mineral resources (125 kt grading 11.17 g/t Au and 59.89 g/t Ag). Inferred mineral resources consist of 202 kt grading 7.80 g/t Au and 48.55 g/t Ag. 3. 1,370 claims totaling 7,601 ha (18,783 acres) of patented mining claims (22 of which are leased patented claims) and a further 110 mining claims of approximately 731 ha (1,807 acres). 4. Refer to the full text of San Antonio Technical Report for the assumptions, qualifications and limitations relating to the San Antonio Gold Project and the San Antonio Technical Report. Indicated resources contain 577 koz Au (14.9 Mt grading 1.20 g/t Au), and Inferred resources 543 koz (16.5 Mt grading 1.02 g/t Au). Brownfield properties with existing accessible infrastructure and meaningful exploration upside Canada USA Mexico CARIBOO GOLD PROJECT TINTIC PROJECTBC, Canada 100% ownership Utah, USA 100% ownership SAN ANTONIO PROJECT Sonora, Mexico 100% ownership Status EA Certificate (granted Q4 23) Permits (granted Q4 24) Optimized FS (Q2 25) PF Financing (Q3 25) Infill Drilling (Q4 25) Reserves / Resources1 2.07 Moz Reserves (Au) 1.61 Moz M&I Resources (Au) 1.86 Moz Inferred Resources (Au) Property Highlights − >1,900 km2 property (83 km strike) − Excellent infrastructure, support of principal Indigenous nations and BC government Status Stockpile processing (complete Q3 23) Advancing permitting Reserves / Resources4 576 koz Indicated Resources (Au) 544 koz Inferred Resources (Au) Property Highlights 5 known deposits with numerous gold exploration targets over 11,338 hectares Status Trixie MRE (completed Mar 24) Trixie Decline (completed Sep 23) Small-scale Heap Leach (underway) Reserves / Resources2 150 koz M&I Resources (Au) 51 koz Inferred Resources (Au) Trixie Highlights − Advancing technical work − Existing surface & UG infrastructure Regional Property Highlights − >20,500 acres of largely patented mining claims3 − 23 past producing mines along 5 km corridor − Prospective targetspotential high-sulphidation epithermal Au-Ag, carbonate replacement and porphyry deposits *Environmental Management Act
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Gradient ODV NYSE TSXV osiskodev.com EXECUTING ON VISION & STRATEGY 6 Source: Bloomberg. Company disclosures. Broker research. 1. Market data as at August 15, 2025. 2. Gold production based on the midpoint of 2025E company guidance or target LOM full nameplate project run-rate (Artemis, Skeena). ODV's estimate based on Cariboo Gold Project's LOM average annual gold production of 202 koz for the first 5 years of production, as described in the 2025 Cariboo FS. Junior and Intermediate Gold Producers Market Capitalization1 $10B $1B $2B $5B $0.4B CAD$ Billion log scale koz Au 100 200 300 400 500 600 700 2025E Annual Gold Production (koz)2 $2.5B $4.0B Sep 2022 Construction Start $358M Jun 2024 Financing Secured $530M $2.4B Mar 2023 Construction Start $858M $6.5B $15B $19B Scarcity of Permitted Assets Cariboo is one of the few fully-permitted projects in a limited universe of developers with gold assets in safe jurisdictions Re-Rate Potential Meaningful re-rate potential through project financing, construction and production phases, as experienced by G Mining, Artemis, Skeena Scalability Current average depth of deposit ~350 meters, with significant opportunity for resource growth $446M Jul 2025 Project Financing
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Gradient ODV NYSE TSXV osiskodev.com US$450 MILLION APPIAN PROJECT FINANCING1 7 1. Refer to ODV news release dated July 21, 2025 (Osisko Development Secures US$450 Million Financing Facility To Develop The Cariboo Gold Project) for further details and terms. US$100 million Initial Draw Conditions: Unconditional, fully drawn on July 21, 2025 Term: 3 years (July 21, 2028) if not rolled into the overall credit facility, otherwise rolls into 8-year term Interest rate: SOFR + 9.50% (steps down to SOFR + 7.50% on subsequent draw) US$350 million Subsequent Draw Conditions: Final investment decision subject to certain customary project milestones and conditions precedent Term: 8 years from closing (July 21, 2033) Interest rate: SOFR + 7.50% Use of Proceeds Repay existing outstanding US$25 million term loan with National Bank of Canada Undertake a 13,000-meter infill drill campaign to further de-risk Project mine planning assumptions Fund pre-construction and construction activities for the development of the Cariboo Gold Project, including certain detailed engineering, procurement, underground development, operational readiness planning, and other early works activities
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Gradient ODV NYSE TSXV osiskodev.com 1.0x 0.8x 0.7x 0.7x 0.6x 0.5x 0.4x 0.4x 0.4x 0.4x 0.3x 0.3x 0.3x 0.3x 0.2x 0.2x 0.1x 0.1x SKE PPTA NFG GTWO RUP WRLG SGD PRB PRYM BRVO ITR SEA TLG FF LGD CAPITAL STRUCTURE SNAPSHOT 8 Source: Company disclosures. Broker research. S&P CapitalIQ. 1. Market data, including share price and share count, as at August 15, 2025. 2. Financial information presented as at June 30, 2025. 3. 7.75M C$14.75 warrants (exp 2-Mar-27); 11.36M US$10.70 warrants (exp 27-May-27); 7.84M C$8.55 warrants (exp 2-Mar-26); 51.11M US$3.00 warrants (exp 1-Oct-29); 49.53M US$2.56 warrants (exp 15-Aug-27). 4. Net of Electric Elements Mining Corp. 5. Includes long-term debt and lease liabilities pertaining to equipment financing. Subsequent to Q2 2025 completed US$100 million initial draw from Appian project financing, repaid US$25 million (C$33.9 million) outstanding term loan with National Bank, and completed a US$203 million private placement financing. Osisko Development Corp.1,2 Shareholder Ownership Relative Valuation: Price / NAV Analyst Coverage Current Share Price (closing price on August 15, 2025) C$3.50 /share Basic Shares Outstanding 238.6 million Options, DSUs, and RSUs 8.6 million Warrants3 127.6 million Fully Diluted Shares Outstanding 374.8 million Market Capitalization – Basic C$835.0 million Cash & Cash Equivalents C$46.3 million Investment Holdings (marketable securities) 4 C$25.3 million Total Debt5 C$43.8 million Enterprise Value – Basic C$807.2 million 14% OR Royalties 24% Public float 45% Institutional Investors (PNAV, x) Mid-tier Prod. Junior Prod. 1% Insiders & Management (~3% fully-diluted) 16% Double Zero Capital
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Gradient ODV NYSE TSXV osiskodev.com CARIBOO GOLD PROJECT British Columbia, Canada 100% Ownership 9 Double Tap Gesture with solid fill Virtual Tour 9ODV NYSE TSXV osiskodev.com Video camera outline Watch Video
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Gradient ODV NYSE TSXV osiskodev.com Two prospective mineralized trends over 83 km strike (>185,000 ha property) with 700 km drilled since 2016 Completed a Feasibility Study envisioning a single-phase build and a 10-year mine life. Base case after-tax NPV5% of $943 mm, and IRR of 22.1%, with production of up to 223 koz/yr and US$1,157/oz AISC Brownfield site, year-round access, infrastructure and work force, and strong support from the BC government and Indigenous nations Key Milestones: EA Certificate ; Permits ; Optimized FS ; Project Finance ; Infill Drilling (Q4 25) CARIBOO GOLD PROJECT: ASSET SNAPSHOT 10 1. Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. Mineral reserves include probable reserves 2.071 Moz Au (17.815 Mt grading 3.62 g/t Au). Mineral resources include in the measured category, 8 koz Au (47 kt grading 5.06 g/t Au); in Indicated, 1.604 Moz Au (17.332 Mt grading 2.88 g/t Au); in Inferred, 1.864 Moz Au (18.774 Mt grading 3.09 g/t Au). M&I resources are exclusive of mineral reserves. Developing a mining camp in the under-explored Cariboo gold belt Barkerville Wells Quesnel QR Mill Gibraltar Mine Mt Polley Mine ODV Mineral Tenure >185,000 ha property Mosquito Shaft Valley NE Cow SE Cow Lowhee BC Vein KL Wells Barkerville Barkerville Mountain Cow Mountain Island Mountain Classification Tonnes (000’s) Gold Grade (g/t) Contained Gold (000’s oz) Probable reserves 17,815 3.62 2,071 Measured resources 47 5.06 8 Indicated resources 17,332 2.88 1,604 Measured & indicated 17,380 2.88 1,612 Inferred resources 18,774 3.09 1,864 Reserves & Resources1 OWNERSHIP LOCATION / LAND PACKAGE MINE TYPE METALS STAGE 100% ODV BC, Canada >185,000 ha Underground Gold Permits (Nov-24) FS (Apr-25)
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Gradient ODV NYSE TSXV osiskodev.com 2025 OPTIMIZED FEASIBILITY STUDY HIGHLIGHTS 11 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. 1. Based on base case USDCAD 1.35 exchange rate. 2. Based on USDCAD exchange rate of 1.35 under base case and 1.40 under spot case. 3. Mineral reserves include probable reserves 2.071 Moz Au (17.815 Mt grading 3.62 g/t Au). Mineral resources include in the measured category, 8 koz Au (47 kt grading 5.06 g/t Au); in Indicated, 1.604 Moz Au (17.332 Mt grading 2.88 g/t Au); in Inferred, 1.864 Moz Au (18.774 Mt grading 3.09 g/t Au). M&I resources are exclusive of mineral reserves. *Non-IFRS Measure. See Cautionary Statements – Non-IFRS Measures. 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. All $ figures in CAD, unless otherwise noted (USDCAD 1.35 base case) BASE $2,400/oz | SPOT $3,300/oz 10 YEAR MINE LIFE Based on current reserves only $0.94B | $2.07B After-tax NPV5%2 190 KOZ / YEAR LOM AVG 202 koz/yr in the first 5 years BASE $2,400/oz | SPOT $3,300/oz 22.1% | 38.0% After-tax IRR2 H2 2027 FIRST GOLD 2028 first full year of production US$1,157/OZ AISC* US$947/oz total cash cost* 1.89 MOZ RECOVERED 92.6% total recovery rate LOM $881M INITIAL CAPEX ~US$652M initial capex1 M&I Resources | Inferred3 1.61 MOZ | 1.86 MOZ Significant conversion potential
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Gradient ODV NYSE TSXV osiskodev.com INFILL DRILLING AND UNDERGROUND DEVELOPMENT 12 1. Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. Mineral reserves include probable reserves 2.071 Moz Au (17.815 Mt grading 3.62 g/t Au). 13,000-metre infill drill program underway in the Lowhee Zone expected to be completed by Q4 2025 Lowhee Cow Valley Shaft Mosquito Cariboo Reserve stopes1 2,071 koz (17.8 Mt at 3.62 g/t Au) Infill Drill Program Ramp Progress (1,172 m, 100%) Completed main decline ramp Visible sulfide mineralization within the bulk sample stope area development › 13,000-metre infill drill program part of the Appian project financing obligation › Expected to provide a comprehensive data set to inform resource modeling, mine planning and stope design › Develops a systematic approach for underground mining › Anticipated completion by end of Q4 2025 Visible near-vertical veining in bulk sample area Plan View Infill Drilling Fans Stopes in Mine Plan
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Gradient ODV NYSE TSXV osiskodev.com LOWHEE UNDERGROUND 2025 13
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Gradient ODV NYSE TSXV osiskodev.com PROJECT LOCATION & REGIONAL INFRASTRUCTURE 14 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. 10 km Insights Large land package: total mineral tenure >185,000 hectares Brownfield site with year-round access, infrastructure and work force Grid power: allocated 22 MW from BC Hydro power at 6.7¢ per kWh — 69kV 70km transmission line to be constructed Accessible year round via Highway 26 and located near major towns with access to skilled labour Significant infrastructure already in place with fully permitted and functional QR mill, equipment (roadheader, ore sorter, water treatment plant), lodging facilities Gibraltar Mine Mt Polley Mine
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Gradient ODV NYSE TSXV osiskodev.com ENVIRONMENTAL ASSESSMENT Early Engagement Detailed Project Description EA Readiness Decision Process Planning Application Development and Review EAO* Review of Revised Application Effects Assessment Recommendation & Decision PERMIT APPLICATION Mine Review Committee (MRC) Screening MRC Review Drafting of initial reports, permits, conditions Review of draft materials by MRC and ODV Finalization of reports, permits, conditions BC Mines Act permits (granted Nov 20) EMA permits (granted Dec 12)1 EA Certificate CARIBOO PROJECT PERMITTING: SUCCESSFULLY COMPLETED 15 *Environmental Assessment Office (EAO) 1. The Environmental Management Act permits pertain to any Project-related discharge activities to the environment, including water and air, and the framework and limitations thereof, within the areas outside of the immediate mine site boundaries. These primarily relate to activities during project operations. BC Mines Act permits granted on Nov 20, 2024 — main permits for project construction & operation H1 H2 2020 Submission of Detailed Project Description ODV Joint Application Submission Decision Revised Application Submission Referral H1 H2 2021 2022 Q1 Q2 Q3 Q4 2023 Q1 Q2 Q3 Q4 2024 Q1 Q2 Q3 Q4 GRANTED GRANTED
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Gradient ODV NYSE TSXV osiskodev.com OUTLOOK AND INDICATIVE TIMELINE 16 Indicative timeline contingent on securing of project financing and a positive final investment decision on the Cariboo Gold Project. Timeline remains subject to change depending on availability of capital to advance technical work, among other considerations. Project Financing / Final Investment Decision (FID) Detailed Engineering / Procurement Underground Development Construction Ramp up & First Gold 9 months 12 months 12 months
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Gradient ODV NYSE TSXV osiskodev.com 50 199 223 207 207 176 181 183 177 171 112 3.90 3.80 4.16 3.91 3.96 3.36 3.52 3.50 3.40 3.29 3.00 -1 1 2 3 4 5 6 7 8 9 10 Year Gold Payable Production (koz) Head Grade (g/t Au) 2025 FEASIBILITY PRODUCTION PROFILE Production profile based on current 2.07 Moz of Probable Reserves1 only 17 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. 1. Mineral reserves include probable reserves 2.071 Moz Au (17.815 Mt grading 3.62 g/t Au). 2. Payable gold production. 190 KOZ/YR LOM average2 202 KOZ/YR First 5 years average2 Significant upside potential from resource conversion and exploration Gold Production & Head Grade
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Gradient ODV NYSE TSXV osiskodev.com Annual Gold Production (koz Au) TOP CANADIAN GOLD MINES/PROJECTS 18 Source: Company disclosures. ODV's estimate based on 2025 Cariboo FS. Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. Eagle River, Seabee, Red Lake, Goldex, Timmins, Hemlo, Wasamac, Lamaque, Young-Davidson, Musselwhite, Macassa, Back River, LaRonde, Eleonore, Brucejack, Island, Porcupine, Meliadine, Meadowbank, Detour, Cote, Malartic, Courageous Lake, Greenstone, Springpole, Eskay Creek, Blackwater, Rainy River, Windfall, Valentine Lake, Odyssey. Cariboo is well positioned among top Canadian underground gold mines/projects with strong upside potential in the long run 113 124 131 143 155 169 174 190 195 197 201 202 212 223 229 240 258 279 284 287 306 307 324 332 365 379 438 453 505 656 672 Red Lake Timmins Goldex Hemlo Island Wasamac Young- Davidson Cariboo Valentine Lake Lamaque Courageous Lake Cariboo Musselwhite Back River Rainy River Eleonore Brucejack Macassa Porcupine Springpole Windfall LaRonde Eskay Creek Greenstone Cote Meliadine Blackwater Odyssey Meadowbank Malartic Detour Cariboo LOM Avg. Cariboo First 5 yrs Underground Open pit Cariboo is a scalable asset Based on 2025 FS projections, Cariboo is already among the top underground gold assets in Canada, with significant upside potential
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Gradient ODV NYSE TSXV osiskodev.com GLOBAL GOLD COST CURVE POSITIONING 19 Source: Based on S&P's Global Market Intelligence, Metals & Mining, 2024 global gold cost curve for TCC and AISC. Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. 2024 Global Total Cash Cost Curve (US$/oz) 2024 Global All-in Sustaining Cost Curve (US$/oz) Cariboo is positioned in the lower half of the global cost curve for gold mines on TCC and AISC Well situated relative to notable Canadian underground operations Island ($592) Lamaque ($711) Macassa ($748) Goldex ($923) Meadowbank ($938) Meliadine ($940) LaRonde ($945) Cariboo ($947) Musselwhite ($1,045) Young-Davidson ($1,047) Porcupine ($1,097) Brucejack ($1,254) Eleonore ($1,339) Hemlo ($1,483) Timmins ($1,700) -- $500 $1,000 $1,500 $2,000 $2,500 $3,000 $3,500 -- 25% 50% 75% 100% Percentile (%) Island ($865) Macassa ($907) Meadowbank ($1,120) Meliadine ($1,127) Lamaque ($1,134) Cariboo ($1,157) LaRonde ($1,239) Young-Davidson ($1,314) Goldex ($1,319) Porcupine ($1,437) Musselwhite ($1,541) Brucejack ($1,603) Hemlo ($1,769) Eleonore ($1,811) Timmins ($2,182) -- $500 $1,000 $1,500 $2,000 $2,500 $3,000 $3,500 -- 25% 50% 75% 100% Percentile (%) Cariboo $947/oz Cariboo $1,157/oz
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Gradient ODV NYSE TSXV osiskodev.com CAPITAL COST BREAKDOWN 20 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. 1. Based on base case USDCAD 1.35 exchange rate and US$2,400/oz gold price. Capital costs ($ million) Initial Sustaining Total LOM Underground mine 313 397 710 Water & waste management 98 24 123 Power & electrical 19 — 19 Surface infrastructure 42 1 43 Process plant (MSC) 180 — 180 Construction indirects 95 — 95 Contingency (16.5%) 72 4 76 Capital Costs 819 426 1,246 Pre-production opex 212 — 212 Pre-production revenue (150) — (150) Closure, net — 99 99 Total Capital Cost 881 525 1,406 Insights ~US$652 million upfront capex1 Process plant and related infrastructure designed to accommodate potential future throughput expansions UG development incorporate contingencies via advance and mining rates $313 Underground Mine $180 Process Plant $95 Indirects $98 Water & Waste Management 11% 5% 2% $42 Infrastructure $19 Power $72 Contingency 8% 7% $62 Capitalized Opex, net $881M Initial Capex 36% 20% 11%
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Gradient ODV NYSE TSXV osiskodev.com ROBUST PROJECT ECONOMICS 21 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. *Non-IFRS Measure. See Cautionary Statements – Non-IFRS Measures. Spot case is based on the LBMA gold price as of the close of business on April 23, 2025, rounded to nearest $100/oz and the USDCAD exchange rate is based on the Bank of Canada daily exchange rate, rounded to nearest five cents. after-tax, C$ Base Case US$2,400 Gold | 1.35 FX Spot Case US$3,300 Gold | 1.40 FX Net Present Value (NPV5%) $943 mm $2,066 mm Internal Rate of Return (IRR) 22.1% 38.0% Payback, from first production 2.8 yrs 1.6 yrs Avg. Annual FCF* (LOM) $158 mm/yr $314 mm/yr Avg. Annual FCF* (first 5 years) $296 mm/yr $457 mm/yr $0.61 B $0.94 B $1.93 B $2.59 B $2,100 $2,400 $3,300 $3,900 Gold Price (US$/oz) NPV5% Gold Price Sensitivity After tax, base case USDCAD 1.35 Spot Case 16.5% 22.1% 36.3% 44.5% $2,100 $2,400 $3,300 $3,900 Gold Price (US$/oz) IRR Gold Price Sensitivity After tax, base case USDCAD 1.35 Base Case Base Case Spot Case
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Gradient ODV NYSE TSXV osiskodev.com MINE DESIGN SUMMARY 22 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. Insights Access via two ramps from Cow and Valley Portals >1.2 km of access into Lowhee zone already completed as part of ongoing bulk sample program Maximum vertical depth ~650 meters Mining split into 3 distinct areas: Cariboo North, South, and Deep Bulk tonnage long-hole mining Stope design: min width 3.7 m x 30 m height x length 15-25 m +60% in average stope size vs. 2023 FS to ~5,600 t 24-month development, ramp up to 4,900 tpd over 10 months Each zone is expected to operate independently and provide aggregate ore feed of 4,900 tpd
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Gradient ODV NYSE TSXV osiskodev.com PROPOSED CONCEPTUAL MINE SITE LAYOUT 23 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. Insights Single processing facility at the Mine Site Complex Primary & secondary crushing underground and conveyed to the surface ore sorter Gravity and flotation processing circuits produce two gold concentrates Comminution circuit already purchased Process plant and related infrastructure designed to accommodate potential future throughput expansions
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Gradient ODV NYSE TSXV osiskodev.com MINERALIZATION FAVORABLE TO ORE SORTING 24 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. 1. Average estimated uncapped length weighted grade based upon work completed to date by ODV and verified by ODV's QP. Ore sorting removes marginal material and generates an NPAG waste product at a low opex of C$1-2 per tonne 5.00 g/t 133 g/t Doré Mined Stope ~5,600 t AVERAGE VEIN GOLD GRADE1 MINED GRADE 4,900 tpd 2.82 g/t ORE SORTER TREATMENT 30% 0.14 g/t Ore Sorter Waste Coarse Fines Mill Feed Flotation Gravity Sandstone Low Density Material (~2.5 g/cm3) Unmineralized Waste Pyrite hosted in quartz veins High Density Material (~5 g/cm3) Stopes designed to follow vein corridors 11.0 g/t 3.62 g/t 5.50 g/t 4.45 g/t FINES MATERIAL ORE SORTER CONCENTRATE Insights 481 vein corridors with 2-meter minimum width Gold uniquely pyrite hosted within a high-density network of mineralized quartz veins Ore sorting separates sandstone (waste) from the high- density gold-associated pyrite +42% of mined material removed as non-acid generating waste (used as backfill or for construction) FLOTATION CONCENTRATE 58% 42% 46% 54% 70%
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Gradient ODV NYSE TSXV osiskodev.com PROCESSING FLOWSHEET 25 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. Gravity circuit to recover 46% of gold Crush/screen Sort Grind Gravity / Flotation Dore (gravity) & Flotation Concentrate LOM recovery 92.6% 2025 FS Addition Totals may not add up due to rounding
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Gradient ODV NYSE TSXV osiskodev.com KEY PROCESSING ELEMENTS 26 Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. Insights Crushed material is screened, with fines bypassing the tertiary crusher and reporting directly to the mill feed bin Coarser material is screened into two suitable feed streams for sorting Addition of gravity circuit is expected to recover ~46% of gold in doré ~66 tpd of high-grade flotation concentrate averaging ~133 g/t Au 80% reduction in number of concentrate trucks on local roads 97.75% concentrate payability factor Process Overview 1) Crushing & Screening – Underground primary & secondary jaw crushers – Screen at surface to separate size fractions for sorting 2) Ore Sorting – 2 ore sorters: 1 for the midsize ~10-35mm, and 1 for coarse ~35-75mm. – Fines bypass to the mill feed – Sorter reject material is disposed of as waste rock 3) Grinding – Tertiary crusher for sorted product – Single stage ball mill – Regrinding suing vertical mill 4) Gold Recovery – Froth flotation for primary gold recovery – Rougher flotation at ~190µm and cleaner flotation at 20 - 24µm – Both grinding and regrinding feature centrifugal gravity units in the grinding circuits 4) Tailings – All milled tailings disposed of as paste backfill
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Gradient ODV NYSE TSXV osiskodev.com CARIBOO RESOURCE CONVERSION POTENTIAL Plan & Isometric View – North Shaft Zone 27 Source: Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. 1. Mineral reserves include probable reserves 2.071 Moz Au (17.815 Mt grading 3.62 g/t Au). Mineral resources include in the measured category, 8 koz Au (47 kt grading 5.06 g/t Au); in Indicated, 1.604 Moz Au (17.332 Mt grading 2.88 g/t Au); in Inferred, 1.864 Moz Au (18.774 Mt grading 3.09 g/t Au). M&I resources are exclusive of mineral reserves. Resource Stopes Reserve Stopes Planned Development Plan View 3D View Pink zones represent Reserve stopes Reserves include a total of 2.07 Moz1 An additional 1.61 Moz contained within M&I resources and 1.86 Moz within Inferred resources1
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Gradient ODV NYSE TSXV osiskodev.com CARIBOO EXPLORATION POTENTIAL AT DEPTH 28 Source: Source: Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. 1. Mineral reserves include probable reserves 2.071 Moz Au (17.815 Mt grading 3.62 g/t Au). Mineral resources include in the measured category, 8 koz Au (47 kt grading 5.06 g/t Au); in Indicated, 1.604 Moz Au (17.332 Mt grading 2.88 g/t Au); in Inferred, 1.864 Moz Au (18.774 Mt grading 3.09 g/t Au). M&I resources are exclusive of mineral reserves. LONG SECTION: LOOKING NORTHEAST 4.4 km strikeOPEN OPEN EXISTING RESERVES & RESOURCES POTENTIAL VEIN CORRIDOR EXTENSIONS 2.07 Moz Au at 3.62 g/t Au in Probable Reserves1 1.61 Moz Au at 2.88 g/t Au M&I resources, 1.86 Moz at 3.09 g/t Au Inferred Resources with conversion potential1 Average deposit depth is ~350 m >500 m additional depth potential of known vein corridors adjacent to mine plan untested Mineralized veins intersected at depth to ~900 m and still open 500 m 1 km Conceptual Deposit Model
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Gradient ODV NYSE TSXV osiskodev.com A POTENTIAL GENERATIONAL DISTRICT 29 Source: Company disclosures. 1. Refer to the 2025 Cariboo FS for the assumptions, qualifications and limitations relating to disclosure about the 2025 Feasibility Study on the Cariboo Gold Project. Mineral reserves include probable reserves 2.071 Moz Au (17.815 Mt grading 3.62 g/t Au). Mineral resources include in the measured category, 8 koz Au (47 kt grading 5.06 g/t Au); in Indicated, 1.604 Moz Au (17.332 Mt grading 2.88 g/t Au); in Inferred, 1.864 Moz Au (18.774 Mt grading 3.09 g/t Au). M&I resources are exclusive of mineral reserves. 2. Head grade, production and AISC based on FY24 results (Young- Davidson); reserves consist of proven reserves 2.087 Moz (28.469 Mt grading 2.28 g/t Au) and probable reserves 0.943 Moz (13.287 Mt grading 2.21 g/t). M&I resources consist of measured 0.780 Moz (7.627 Mt grading 3.18 g/t) and indicated 0.406 Moz (5.226 Mt grading 2.41 g/t). Inferred resources of 0.198 Moz (1.911 Mt grading 3.22 g/t). 3. Head grade and production based on FY24 results (FY24 results); AISC were estimated/calculated on the basis of actual FY24 results for total cash costs per ounce plus sustaining capex divided by FY24 production. 4. Reserves consist of proven reserves 0.273 Moz (6.318 Mt grading 1.34 g/t Au) and probable reserves 0.654 Moz (14.085 Mt grading 1.44 g/t). M&I resources consist of measured 0.739 Moz (12.360 Mt grading 1.86 g/t) and indicated 0.955 Moz (22.270 Mt grading 1.33 g/t). Inferred resources of 0.885 Moz (16,946 Mt grading 1.62 g/t). 5. LaRonde Zone 5 reserves consist of proven reserves 0.339 Moz (5.026 Mt grading 2.10 g/t Au) and probable reserves 0.319 Moz (4.241 Mt grading 2.34 g/t). M&I resources consist of indicated resources 0.817 Moz (11.094 Mt grading 2.29 g/t). Inferred resources of 0.960 Moz (7.187 Mt grading 4.15 g/t). Long Section of Selected Canadian Operating Underground Mines vs. Cariboo Gold Head Grade (Au) 3.62 g/t 2.08 g/t 1.55 g/t 3.62 g/t Gold Production 190 koz 174 koz 131 koz 307 koz AISC (US$/oz) $1,157 / oz $1,314 / oz ~$1,319 / oz ~$1,239 / oz Reserves 2.07 Moz 3.03 Moz 0.79 Moz 0.66 Moz Resources (M&I | Inf) 1.61 | 1.86 Moz 1.19 | 0.20 Moz 1.69 | 0.89 Moz 0.82 | 1.24 Moz OSISKO DEVELOPMENT Cariboo Deposit1 ALAMOS GOLD Young-Davidson2 AGNICO EAGLE Goldex3,4 AGNICO EAGLE LaRonde Zone 53,5 Cariboo's deposit has only been drilled to an average depth of ~350 m and remains open along strike and at depth 4.4 km strike STRONG POTENTIAL AT DEPTH 1.1km 0.8km 1.5km ~8,000 tpd ~8,000 tpd ~3,300 tpd
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Gradient ODV NYSE TSXV osiskodev.com 14 km trend from Mosquito Creek to Proserpine has exploration potential down to 1500m depth The sandstone unit hosting the CGP mineral resources was mapped and modelled and is believed to be continuous along the entire 14 km trend Cariboo Deep Assay highlights: – 18.5 g/t Au over 21m at 540m vertical below surface (IM-17-191)1 – 14.8 g/t Au over 12m at 430m vertical below surface (CM-17-084)2 – 13.52 g/t Au over 6m at 370m vertical below surface (CM-18-148)3 Drilling on Proserpine Mountain in 2019 (2,675 meters in 6 holes) intersected 17.78 g/t Au over 5.60 meters including 112 g/t over 0.60 m, 26.08 g/t over 3.00 m including 84.90 g/t over 0.90 m4 – 2,917 m drilled in 5 holes intersected 7.96 g/t over 9.0 m, including 19.15 g/t over 0.60 m5 The scale of these prospects could potentially host a deposit similar to the CGP IMMEDIATE EXPLORATION UPSIDE AT CARIBOO 30 1. Refer to BGM news release dated Nov 28, 2017 (BGM Intersects 14.69 G/T Au Over 28.50 Metres at Shaft Zone). 2. Refer to BGM news release dated Mar 20, 2018 (BGM Intersects 22.11 G/t Au Over 5.85 Meters At Valley Zone). 3. Refer to BGM news release dated Dec 6, 2018 (Barkerville Gold Intersects 24.06 g/t Gold Over 6.45 Meters and Extends Vein Corridors at Depth). 4. Refer to OGR news release dated Oct 5, 2020 (Osisko Announces Multiple New High-grade Gold Discoveries Adjacent To Main Deposits At The Cariboo Gold Project). 5. Refer to ODV news release dated Feb 9, 2021 (Osisko Development Announces Expansion of Proserpine Discovery to 1.5 km Strike Length). Cariboo Gold Project Warspite Proserpine Mountain Williams Creek Barkerville Mountain Wilkinson Victory Bell-Independence 4 km strike 10 km strike 1500 m potential depth Permit boundary
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Gradient ODV NYSE TSXV osiskodev.com DEVELOPING A MINING CAMP 31 1. Source: DigiGeodata as at Dec 31, 2019. Total gold endowment includes historical production (73 Moz), reserves (19 Moz), and M&I resources (21 Moz). Including inferred resources (70 Moz) total endowment increases to 143 Moz. 2. Total land package of ~1,900 km2 over all claims, including those around QR mill. Cariboo hosts two main trends over 83 km in combined strike length Val d'Or Mining Camp 1,400 km2 area with +110 Moz of gold1 Westwood LaRonde Canadian Malartic Kiena Goldex Lamaque districts shown to scale Cariboo Camp Cariboo Land Package >1,550 km2 with at least 3 similar size footprint targets to Cariboo2 Land position > Val d'Or district District-scale exploration upside in under-explored Cariboo Gold Belt High degree of confidence in geological model with anomalous gold values >2.0 g/t Au in ~80% of drill holes >185,000 ha property with 83 kilometers strike of gold targets ~700,000 meters drilled since 2016 Strong support from the BC government Year-round exploration and access, infrastructure and work force 0 km 30 km
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Gradient ODV NYSE TSXV osiskodev.com TINTIC PROJECT Utah, USA 100% Ownership 32 Double Tap Gesture with solid fill Virtual Tour 32ODV NYSE TSXV osiskodev.com
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Gradient ODV NYSE TSXV osiskodev.com TINTIC PROJECT: ASSET SNAPSHOT 33 1. 1,370 claims totaling 7,601 ha (18,783 acres) of patented mining claims (22 of which are leased patented claims) and a further 110 mining claims of approximately 731 ha (1,807 acres). Highly Productive Historical Mining District OWNERSHIP LOCATION / LAND PACKAGE MINE TYPE METALS STAGE 100% ODV Utah, USA >20,500 acres of largely patented claims1 Underground Gold, Silver Cu, Pb, Zn Trixie MRE (Q1 2024) Located 95 km south of Salt Lake City, Utah, ~65 km from the prolific Bingham Canyon copper mine, one of the largest operating open pit mines globally Fast-tracking Trixie while advancing other prospective exploration targets, including high quality porphyry, epithermal and CRD targets Second largest metal producing district in Utah following Bingham, with 23 past-producing mines located within Tintic property Key Milestones: 2024 Trixie MRE (Q1 2024) ; Decline to Trixie main level (complete) ; Small-scale heap leaching; Advancing technical work Eureka Provo Salt Lake City Bingham Canyon Mine Eureka North Lily Tintic Standard Burgin Mine Trixie
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Gradient ODV NYSE TSXV osiskodev.com TRIXIE INITIAL MINERAL RESOURCE ESTIMATE ("MRE")1 34 1. Refer to the full text of the Tintic Technical Report for the assumptions, qualifications and limitations relating to disclosure on the 2024 Trixie MRE. The 2024 Trixie MRE comprises six mineralized zones within the greater Trixie deposit, including T2, T3, T4, Wild Cat, 40 Fault and 75-85 over a strike length of 530 m, a maximum width of 105 m and to a maximum depth of 195 m for the deposit and is 350 m from surface. These dimensions are for the overall size of the mineralized zone structures, with the 2024 Trixie MRE blocks contained within a smaller 440 m strike length, 60 m total width and 195 m depth footprint. RESOURCE CATEGORY TONNES (000’s) METAL GRADE CONTAINED METAL (g/t Au) (g/t Ag) (000’s oz Au) (000’s oz Ag) MEASURED 120 27.36 61.73 105 238 INDICATED 125 11.17 59.89 45 240 MEASURED & INDICATED 245 19.11 60.80 150 478 INFERRED 202 7.80 48.55 51 315 Deposit reasonably stable to COG variation CUT-OFF GRADE VARIATION 156 150 141 136 16.6 19.1 24.0 27.6 3.50 4.32 6.00 7.00 Cut-off Grade (g/t Au) M&I RESOURCES 60 51 39 32 6.7 7.8 9.7 11.0 3.50 4.32 6.00 7.00 Cut-off Grade (g/t Au) INFERRED RESOURCES Resources (koz) Grade (g/t Au) HIGH-GRADE DEPOSIT MRE comprises small footprint (440 m length x 60 m width x 195 m depth)1 MEANINGFUL UPSIDE ~10% of the main Trixie area explored to date +57% MEASURED RESOURCES Contained gold ounces in measured resources increased to 105 koz vs. 2023 Trixie MRE
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Gradient ODV NYSE TSXV osiskodev.com TRIXIE UG RAMP DEVELOPMENT: 100% COMPLETE 35 1. Morris, H. T. & Lovering, T. S. General geology and mines of the East-Tintic mining district, Utah and Juab counties, Utah. U.S. Geological Surv. Prof. Pap. 1024, (1979). Complete as of September 2023 Enables bulk extraction at higher tonnage by providing underground access to a modern, mechanized fleet Accelerates potential development and exploration activities at lower levels Decline size 16x16 ft. (5x5 m), with muckbays excavated every 300 ft. (100 m) – potential to use for UG exploration platforms RAMP DEVELOPMENT: ~1,390 M (4,550 ft.) 3 Historic Mineralized Zones Open at Depth and Strike Ramp Entrance 1 2 Breakthrough to 625 ft. level Trixie decline ramp breakthrough 3 Ramp Construction 756 ORE SHOOT 610 ORE SHOOT SOUTH SURVEY VEIN Developed over 900 ft. (275 m) strike and 1,000 ft. (300 m) vertical Mined for flux by Kennecott Average grades 6 to 8 g/t Au1 Focus of 2001-2002 mining activity Mined down to the 1,200 ft. level Average grades 21 g/t Au1 Mined by Kennecott in the 1980’s Extends for 3,400 ft. (1,030 m) south of the main shaft 756 Ore Shoot TRIXIE RAMP Main Shaft Vent Shaft T2, T4 South Survey Vein 1350 L 1200 L 1050 L 900 L 750 L 625 L 75-85 Ore Shoot 610 1 2 3
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Gradient ODV NYSE TSXV osiskodev.com TRIXIE EXPLORATION POTENTIAL 2024 Trixie MRE represents a small footprint of the overall underground potential 36 1. Refer to the full text of the Tintic Technical Report for the assumptions, qualifications and limitations relating to disclosure on the 2024 Trixie MRE. The 2024 Trixie MRE comprises six mineralized zones within the greater Trixie deposit, including T2, T3, T4, Wild Cat, 40 Fault and 75-85 over a strike length of 530 m, a maximum width of 105 m and to a maximum depth of 195 m for the deposit and is 350 m from surface. These dimensions are for the overall size of the mineralized zone structures, with the 2024 Trixie MRE blocks contained within a smaller 440 m strike length, 60 m total width and 195 m depth footprint. Empire State building for scale (~4 football fields) Trixie MRE SOUTH NORTH 2024 TRIXIE MRE1 440 meter strike length 60 meter width 195 meter depth Looking East
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Gradient ODV NYSE TSXV osiskodev.com DRILLING AND CHIP SAMPLING HIGHLIGHTS 37 1. Refer to ODV news release dated November 30, 2022 (Osisko Development Reports Underground Sampling Results At Trixie, Tintic Project). 2. Refer to ODV news release dated January 11, 2023 (Osisko Development Extends T2 Mineralization 55 Meters Down Dip At Trixie, Tintic Project). 3. Refer to ODV news release dated April 3, 2023 (Osisko Development Reports 2022 Drill Results At Trixie). 4. Refer to ODV news release dated May 4, 2023 (Osisko Development Reports 2022 Drill Results At Trixie). 5. Refer to ODV news release dated May 17, 2023 (Osisko Development Reports Exploration Results at Trixie and Outlines 2023 Drill Program at Tintic Project). 6. Refer to ODV news release dated February 22, 2024 (Osisko Development Intercepts 610 g/t Gold Over 0.46 Meters in Underground Drilling At Trixie, Tintic Project). Completed a total of 6,028 m (19,776 ft) of Trixie exploration and delineation drilling in 2023 Select DrillingSelect Chip Sampling HOLE ID (CH) WIDTH (m) GRADE (g/t) SILVER GOLD 11871 0.73 209.8 1,017.0 11801 0.55 – 4,186.5 11631 0.61 6,699.0 5,197.8 11141 1.52 1,224.9 1,553.1 including 0.82 2,263.4 2,873.1 11101 2.07 316.0 2,800.1 including 1.22 528.9 4,757.4 11051 0.40 102.4 1,769.3 11021 0.37 1,560.0 2,202.9 10111 0.55 911.1 2,352.2 10071 1.01 2,546.1 1,381.6 13512 2.29 1,146.5 2,311.2 12562 0.91 78.7 3,901.3 13262 0.82 1,587.6 3,419.9 HOLE ID WIDTH (m) GRADE (g/t) SILVER GOLD TUG-625-0292 3.81 21.48 25.95 Including 1.52 41.80 43.00 TUG-625-0602 5.33 439.26 12.58 TUG-625-0652 1.22 511.00 264.00 TUG-625-0692 1.22 84.30 65.50 Including 0.30 246.00 231.00 TUG-625-0873 6.25 404.19 28.72 TUG-625-0863 4.57 96.98 27.26 TUG-625-0374 2.44 90.24 53.27 TUG-625-0364 3.35 30.89 36.81 TRXU-DD-23-0035 6.86 231.46 62.82 TRXU-DD-23-072A6 8.99 167.64 66.04 Including 0.46 1,523.00 610.00 TRXU-DD-23-0686 9.45 151.04 23.89 Trixie Underground Long Section In 2023, the Company completed a total of 6,028 m (19,776 ft) of underground drilling in 73 diamond drill holes at Trixie. Assays were finalized up to hole TRXU- DD-23-069 and were included in the 2024 Trixie MRE The new drilling, mapping and historical data compilation improved the interpretation and revealed significant potential for parallel high-grade gold fissure zones similar to T2 adjacent to existing mine development Much of the Trixie area remains unexplored
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Gradient ODV NYSE TSXV osiskodev.com EAST TINTIC REGIONAL EXPLORATION POTENTIAL Highly prospective 5 km long corridor with 23 historic mines, extensive legacy datasets 38 1. Source: History, Geology, and Production of the Tintic Mining District, Juab, Utah and Tooele Counties; K. Krahulec, D. F. Griggs; 2006. 2. Short tons. High-Sulphidation Epithermal Au-Ag Epithermal vein / breccia systems hosted primarily within the basal Tintic Quartzite host rock, found at the Trixie, Eureka Standard and the deeper levels of North Lily mines Carbonate Replacement ("CRD") Ag-Pb-Zn Replacement of reactive limestone more distal from causative porphyry centers on the margins of district Accounts for most historical production within Tintic, including Burgin, Tintic Standard, and North Lily mines PORPHYRY Cu-Au-Mo POTENTIAL Advanced argillic alteration in a NNE trend of remnant lithocaps potentially marks a lineament of porphyry centers at depth. Historic drill testing intersected low grade porphyry mineralization TRIXIE MAIN SHAFT CRD Target GOLD 2.8 MOZ SILVER 285 MOZ Main East East Main Copper 128kt2 Main East East East Main MainLead 1.16Mt2 Zinc 259kt2 Historic Production1
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Gradient ODV NYSE TSXV osiskodev.com SAN ANTONIO PROJECT Sonora, Mexico 100% Ownership 39 39ODV NYSE TSXV osiskodev.com
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Gradient ODV NYSE TSXV osiskodev.com SAN ANTONIO PROJECT: ASSET SNAPSHOT 40 1. Refer to the full text of the San Antonio Technical Report for the assumptions, qualifications and limitations relating to the San Antonio Gold Project and the San Antonio Technical Report. Located 160 km from airport and towns of Hermosillo and Obregon in mining-friendly Sonora Constructed a heap leach pad and a carbon in column plant at the end of 2021 to process stockpiled mineralized material − 1.1 Mt stockpile grading 0.58 g/t Au placed on the leach pad − 13,591 ounces sold as at Sep 30, 2023 (complete) Gold mineralization identified over 10 km strike Mine infrastructure and water on site Awaiting next steps from the Mexican government on permitting Under strategic review, including potential for a financial or strategic partner in the asset or for a full or partial sale of the asset Asset Highlights Mineral Resources1 MATERIAL INDICATED INFERRED Tonnes Grade Contained Tonnes Grade Contained (Mt) (g/t Au) (koz Au) (Mt) (g/t Au) (koz Au) Oxide 2.7 0.89 77 4.6 0.74 111 Transitional 1.8 1.02 59 2.1 0.9 61 Sulfide 10.4 1.31 441 9.8 1.18 371 TOTAL 14.9 1.20 576 16.5 1.02 544 Mexico Sonora Mexico La Colorada (Argonaut Gold) La India (Agnico) Mulatos (Alamos) Santana (Minera Alamos) San Antonio ODV 0 20 km Production Development N 11,338 ha land package
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Gradient ODV NYSE TSXV osiskodev.com APPENDIX 41
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Gradient ODV NYSE TSXV osiskodev.com EXPERIENCED LEADERSHIP TEAM 42 • Sean Roosen (Executive Chair) • Charles Page • Michèle McCarthy • Duncan Middlemiss • David Danziger • Stephen Quin • Susan Craig BOARD OF DIRECTORSDAVID ROULEAU, VICE PRESIDENT, PROJECT DEVELOPMENT • Seasoned executive with +35 years of operational and management experience in the mining industry across projects and operations. Served as VP Mine Optimization and Strategic Planning at Victoria Gold overseeing the Brewery Creek Project and other strategic initiatives • VP of Operations for Barkerville Gold Mines (2016-2018); Taseko Mines (2010-2016); and spent 17 years with Teck Cominco • Holds a BSc in Mine Engineering (South Dakota School of Mines) and a Mine Technology Diploma (Haileybury School of Mines) LAURENCE FARMER, GENERAL COUNSEL & VP STRATEGIC DEVELOPMENT • Over 10 years of experience in investment banking & corporate law with RBC Capital Markets and Norton Rose Fulbright LLP • Previously Senior Counsel of Osisko Gold Royalties PHILIP RABENOK, VICE PRESIDENT, INVESTOR RELATIONS, CFA • Over 10 years of transactional, capital markets, and corporate experience in the resources sector, most recently in an Investor Relations role at IAMGOLD Corp. • Previously worked in mining investment banking and equity research at Société Générale and Scotiabank SEAN ROOSEN, CHAIR & CEO • Founding member of Osisko Mining Corporation (2003-2014) • Responsible for developing the strategic plan for the discovery, financing and development of the Canadian Malartic Mine • Led the efforts for the maximization of shareholders’ value in the sale of Osisko Mining Corporation, that resulted in the creation of Osisko Gold Royalties • Former Chairman of Osisko Mining Corp. – partner in the development of Windfall CHRIS LODDER, PRESIDENT • 30 years’ experience working on and managing Greenfields exploration, Brownfields exploration, and mine development • Led teams responsible for discoveries of 34+ Moz of gold • President and CEO of Barkerville Gold Mines until its acquisition by Osisko Gold Royalties in 2019 ALEXANDER DANN, CFO, CPA • 25 years of experience leading finance operations and strategic planning for companies in the mining and manufacturing sectors • He obtained his Chartered Accountant designation in 1995, and holds a Bachelor degree in Business Administration from L’Universite Laval in Quebec
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Gradient ODV NYSE TSXV osiskodev.com RESPONSIBLE MINE DEVELOPMENT 43 Committed to responsible mining practices, strong relationships, and mutual support with all partners ▪ Osisko Development constructed two water treatment plants to treat contact water and effluent ▪ Permitting of the Reclamation Closure Plan for Mosquito Creek is underway ▪ Open and transparent dialogue with the Ministry of Mines and Critical Minerals and Ministry of Environment and Parks ENVIRONMENT ▪ Positive permitting climate in central BC given dearth of well-paying jobs from logging industry slowdown ▪ Completed the EA Application Review in January 2022 ▪ Environmental Assessment Certificate granted in October 2023 ▪ Mines Act permits granted in November 2024, Environmental Management Act permits granted in December 2024 PERMITTING ▪ Positive relationship with Lhtako Dené Nation since 2015. Agreements include engagement protocol (signed in 2016), relationship agreements (2016) and life of project agreement (2020) ▪ Participation agreement sign with the Williams Lake First Nation in July 2022 ▪ The Company is working towards an agreement with the Xatśūll First Nation, with whom it continues to engage and consult INDIGENOUS NATIONS ▪ Actively involved in the Wells community ▪ Provided funding to local organizations in support of various initiatives, including: Wells Community Foundation; Island Mountain Arts; Wells and Area Community Association and others ▪ Involved in the various activities in the Barkerville Historic Town (initiated the collection of funds in support of the development of an underground mining exhibit) COMMUNITY
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Gradient ODV NYSE TSXV osiskodev.com CARIBOO 2025 FEASIBILITY STUDY METRICS 44 1. Total may not add up due to rounding. 2. Cash costs, all-in sustaining costs per ounce and free cash flow are non-IFRS measures or ratios. Refer to "Non-IFRS Financial Measures" for more information. Total cash costs are presented on a per ounce payable basis inclusive of total operating costs mining costs, processing costs, site G&A costs, royalties, smelting, refining, and transports costs. AISC are presented on a per ounce payable basis and include cash costs plus sustaining and closure costs. 3. Closure costs are shown net of salvage value. 4. Pre-final investment decision capital costs total $38.6 million. Cariboo Gold 2025 FS – Project Operating and Financial Metrics Assumptions units 2025 FS Gold price US$/oz 2,400 Exchange rate USDCAD 1.35 Discount rate % 5.0% Production Mine life yrs 10.0 Total ore mined kt 17,815 Peak annual throughput tpd 4,900 Average gold head grade g/t Au 3.62 Total contained gold koz 2,071 Avg. gold recovery % 92.6% Total recovered gold, payable koz 1,894 Avg. gold production, LOM koz/yr 190 Avg. gold production, first 5 yrs koz/yr 202 Operating Unit Costs Underground mining $/t mined 62.3 Processing $/t mined 23.2 Water and waste management $/t mined 5.0 Electrical transmission line $/t mined 4.9 General and administrative $/t mined 15.4 Total unit operating costs $/t mined 110.7 Total operating costs $ mm 1,921 Royalty payments $ mm 292 Offsite charges $ mm 143 Operating Costs Total cash costs2 US$/oz $947 AISC2 US$/oz $1,157 Capital Expenditures Initial costs $ mm 881 Expansion costs $ mm — Sustaining costs $ mm 426 Closure costs, net3 $ mm 99 Total capex $ mm 1,406 Economics (after-tax) Total free cash flow, LOM2 $ mm 1,577 Net Present Value (NPV5%) $ mm 943 Internal Rate of Return (IRR) % 22.1% Payback, from commercial production yrs 2.8 Average free cash flow, first 5 yrs2 $ mm 296 Average free cash flow, LOM2 $ mm 158 Cariboo Gold 2025 FS – Operating Costs Metric Total LOM Unit Cost Unit Cost Split ($ mm) ($/t mined) (US$/oz) (%) Mining 1,080 62.25 434 56% Processing 403 23.21 162 21% Water and waste management 86 4.97 35 4% Electrical transmission line 86 4.93 34 4% General and administrative 266 15.36 107 14% Total site operating costs 1,921 110.73 772 100% Cariboo Gold 2025 FS – Total Cash Costs and All-in Sustaining Costs Metric Total LOM Unit Cost ($ mm) (US$/oz) Total site operating costs 1,921 772 Royalties 292 117 Transport and refining costs 143 58 Total cash costs1 2,356 947 Sustaining costs, LOM 426 171 Equipment salvage value (36) (14) Reclamation and closure costs 135 54 All-in sustaining costs1 2,881 1,157 Cariboo Gold 2025 FS – Capital Cost Summary Item ($ mm) Initial CAPEX Sustaining CAPEX Total CAPEX Underground mine 313 397 710 Water & waste management 98 24 123 Power & electrical 19 — 19 Surface infrastructure 42 1 43 Process plant – Mine Site Complex 180 — 180 Construction indirects 95 — 95 Contingency (16.5%) 72 4 76 Capital costs 819 426 1,246 Pre-production net revenue (150) — (150) Pre-production operating costs 212 — 212 Equipment salvage value — (36) (36) Reclamation and closure costs — 135 135 Total capital costs 881 525 1,406 1. Pre-final investment decision capital costs total $38.6 million. 1. Total cash costs and all-in sustaining costs per ounce are non-IFRS ratios. Refer to "Non-IFRS Financial Measures" for more information.
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Gradient ODV NYSE TSXV osiskodev.com CARIBOO SELECT HIGH GRADE DRILL RESULTS 45 gxm = grade (g/t) x length (m). 1. Refer to BGM news release dated May 25, 2017 (BGM Intersects 24.13 g/t Au Over 12.70 Metres at Mosquito Creek). 2. Refer to ODV news release dated Jun 2, 2021 (ODV Intersects 23.32 g/t Over 15.0 m on Island Mountain at Cariboo and Announces the Grant of Replacement Restricted Share Units). 3. Refer to ODV news release dated July 6, 2021 (ODV Intersects 35.25 g/t Gold Over 11.0 Meters On Island Mountain At Cariboo). 4. Refer to BGM news release dated March 26, 2019 (BGM Expands Mineralization by 175 Meters at Island Mountain). 5. Refer to BGM news release dated April 17, 2017 (BGM Intersects 19.20 g/t Au over 54.40 metres and 11.42 g/t Au over 28.55 metres at Shaft Zone). 6. Refer to BGM news release dated Sep 6, 2017 (BGM Discovers 53.26 G/T Au Over 11.55 Metres At Shaft Zone). 7. Refer to BGM news release dated Sep 26, 2017 (BGM Intersects 72.23 g/t Au Over 12.05 Metres at Shaft Zone). 8. Refer to ODV news release dated Jun 1, 2022 (ODV Intersects 164.92 g/t Gold over 10.50 meters at Cariboo Gold Project, Valley Zone). 9. Refer to BGM news release dated Aug 31, 2016 (BGM Intersects 10.02 G/T (0.29 oz/t) Au Over 22.20 Metres including 13.01 g/t (0.38 oz/t) Au Over 11.50 Metres In cow Mountain Phase I Drilling). 10. Refer to ODV news release dated Jun 24, 2021 (ODV Intersects 17.16 g/t Gold Over 10.7 Meters at Valley Zone at Cariboo and Announces Annual Grant of Stock Options and RSUs to Officers). 11. Refer to BGM news release dated June 29, 2016 (BGM Intersects 30.98 G/T (0.90 Oz/T) Au Over 6.80 Metres in Cow Mountain Phase I Drilling -- New Gold Extension Discovered). 12. Refer to BGM news release dated Sep 27, 2016 (BGM Intersects 14.59 g/t Au over 10 Metres; Completes Phase I Drilling at Cow Mountain). 13. Refer to OGR news release dated Oct 5, 2020 (Osisko Announces Multiple New High-Grade Gold Discoveries Adjacent to Main Deposits at the Cariboo Gold Project).14. Refer to ODV news release dated Oct 26, 2021 (ODV Intersects 158.40 g/t Au Over 7.75 Meters Including 2,420 g/t Au Over 0.50 Meter at Lowhee Zone). High-grade intercepts are consistently present throughout the entire deposit >50 g/t Au 25 – 50 g/t Au 15 – 25 g/t Au 5 – 15 g/t Au Mosquito Shaft Valley Cow Lowhee 24.13 g/t over 12.7 m1 306 gxm 23.32 g/t over 15.0 m2 350 gxm 35.25 g/t over 11.0 m3 388 gxm 19.34 g/t over 17.9 m4 346 gxm 32.06 g/t over 30.7 m5 984 gxm 53.26 g/t over 11.55 m6 615 gxm 164.92 g/t over 10.5 m8 1,732 gxm 72.23 g/t over 12.1 m7 874 gxm 17.16 g/t over 10.7 m10 188 gxm 14.59 g/t over 10.0 m12 146 gxm 19.03 g/t over 15.2 m14 289 gxm 20.66 g/t over 12.8 m13 264 gxm 22.84 g/t over 8.05 m11 184 gxm 10.02 g/t over 22.2 m9 222 gxm IM-21-024 IM-17-100 IM-21-009 IM-19-013 IM-17-072 IM-17-131 IM-17-151 CM-21-097 BGM-16-451 CM-21-005 BGM-16-359 BGM-16-495 BM-19-105 BM-21-049
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Gradient ODV NYSE TSXV osiskodev.com CARIBOO MINERAL RESERVES & RESOURCES (Measured and Indicated Resources are exclusive of Mineral Reserves) 46 Mineral R&R Probable Reserves Measured Resources Indicated Resources Inferred Resources Deposit Tonnes (000’s) Grade (g/t Au) Ounces (koz Au) Tonnes (000’s) Grade (g/t Au) Ounces (koz Au) Tonnes (000’s) Grade (g/t Au) Ounces (koz Au) Tonnes (000’s) Grade (g/t Au) Ounces (koz Au) Bonanza Ledge — — — 47 5.06 8 32 4.02 4 — — — BC Vein — — — — — — 1,057 3.00 102 596 3.17 61 KL — — — — — — 527 2.80 47 2,514 2.53 205 Lowhee 923 3.52 104 — — — 1,333 2.76 118 486 3.01 47 Mosquito 1,105 3.94 140 — — — 1,553 2.96 148 1,883 3.08 186 Shaft 8,548 3.72 1,022 — — — 6,121 2.92 575 7,457 3.44 826 Valley 3,239 3.59 374 — — — 2,718 2.70 236 2,470 3.01 239 Cow 4,000 3.35 431 — — — 3,991 2.91 374 3,368 2.78 301 Total Reserves / Resources 17,815 3.62 2,071 47 5.06 8 17,332 2.88 1,604 18,774 3.09 1,864 MINERAL RESERVES 1. Totals may not add up due to rounding. 2. The Mineral Reserve estimate follows the 2014 CIM Definition Standards on Mineral Resources and Reserves and the 2019 CIM Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines. 3. Mineral Reserves used the following assumptions: US$1,915/oz gold price, USD:CAD exchange rate of 1.32, and variable cut-off value from 1.70 g/t to 2.0 g/t Au 4. Mineral Reserves include both internal and external dilution along with mining recovery. The external dilution is estimated to be 10.1%. The average mining recovery factor was set at 91.3% to account for ore left in each block in the margins of the deposit. MINERAL RESOURCES 1. The independent and qualified persons for the Mineral Resources estimates, as defined by NI 43-101, are Carl Pelletier, P.Geo., and Tessa Scott, P.Geo. (Norda Stelo). The effective date of the 2025 FS Mineral Resource Estimate is April 22, 2025. 2. These Mineral Resources, exclusive of the reserves, are not Mineral Reserves and do not have demonstrated economic viability. 3. The Mineral Resources estimate follows the 2014 CIM Definition Standards on Mineral Resources and Reserves and the 2019 CIM Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines. 4. A total of 481 vein zones were modelled for the Cow Mountain (Cow and Valley), Island Mountain (Shaft and Mosquito), Barkerville Mountain (BC Vein, KL, and Lowhee) deposits and one gold zone for Bonanza Ledge. A minimum true thickness of 2.0 m was applied, using the gold grade of the adjacent material when assayed or a value of zero when not assayed. 5. The estimate is reported for a potential underground scenario at a cut-off grade of 1.8 g/t Au, except for Bonanza Ledge at a cut-off grade of 3.5 g/t Au. The cut-off grade for the Cow, Valley, Shaft, Mosquito, BC Vein, KL, and Lowhee deposits was calculated using a gold price of US$2,400/oz; a USDCAD exchange rate of 1.35; an underground mining cost of $66.3/t; a processing and transport cost of $30.80/t; a G&A plus Environmental cost of $22.40/t; and a sustaining CAPEX cost of $45.6/t. No changes have been applied for the Bonanza Ledge. The cut-off grade for the Bonanza Ledge deposit was calculated using a gold price of US$1,700/oz; a USDCAD exchange rate of 1.27; an underground mining cost of $79.13/t; a processing and transport cost of $65.00/t; and a G&A plus Environmental cost of $51.65/t. The cut-off grades may be re-evaluated in light of future prevailing market conditions (metal prices, exchange rate, mining cost, etc.). 6. Density values for Cow, Shaft, Lowhee, and BC Vein were estimated using the ID2 interpolation method, with a value applied for the non-estimated blocks of 2.80 g/cm3 for Cow, 2.78 g/cm3 for Shaft, 2.74 g/cm3 for Lowhee, and 2.69 g/cm3 for BC Vein. Median densities were applied for Valley (2.81 g/cm3), Mosquito (2.79 g/cm3), and KL (2.81 g/cm3). A density of 3.20 g/cm3 was applied for Bonanza Ledge. 7. A four-step capping procedure was applied to composited data for Cow (3.0 m), Valley (1.5 m), Shaft (2.0 m), Mosquito (2.5 m), BC Vein (2.0 m), KL (1.75 m), and Lowhee (1.5 m). Restricted search ellipsoids ranged from 7 to 50 g/t Au at four different distances ranging from 25 m to 250 m for each deposit. High grades at Bonanza Ledge were capped at 70 g/t Au on 2.0 m composited data. 8. The gold Mineral Resources for the Cow, Valley, Shaft, Mosquito, BC Vein, KL, and Lowhee vein zones were estimated using Datamine StudioTM RM 1.9 software using hard boundaries on composited assays. The dilution halo gold mineralization was estimated using Datamine StudioTM RM Pro 1.11. The OK method was used to interpolate a sub-blocked model (parent block size = 5 m x 5 m x 5 m). Mineral Resources for Bonanza Ledge were estimated using GEOVIA GEMSTM 6.7 software using hard boundaries on composited assays. The OK method was used to interpolate a block model (block size = 2 m x 2 m x 5 m). 9. Results are presented in situ. Ounce (troy) = metric tons x grade / 31.10348. Calculations used metric units (metres, tonnes, g/t). The number of tonnes were rounded to the nearest thousand. Any discrepancies in the totals are due to rounding effects. Rounding followed the recommendations as per NI 43- 101. 10. The qualified persons responsible for this section of the technical report are not aware of any environmental, permitting, legal, title, taxation, socio-economic, marketing, political, or other relevant factors that could materially affect the Mineral Resource estimate other than those disclosed in this news release and in the Technical Report.
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Gradient ODV NYSE TSXV osiskodev.com SAN ANTONIO MINERAL RESOURCES 47 DEPOSIT CATEGORY TONNES (Mt) GRADE (g/t) CONTAINED METAL SILVER GOLD SILVER (Moz) GOLD (koz) CALIFORNIA Indicated 3.9 2.5 1.22 0.31 153 Inferred 1.6 3.3 1.10 0.17 58 GOLFO DE ORO Indicated 5.7 2.5 1.44 0.46 262 Inferred 6.4 2.5 1.24 0.52 254 HIGH LIFE Indicated – – – – – Inferred 0.8 4.9 0.83 0.13 22 SAPUCHI Indicated 5.4 3.5 0.93 0.61 162 Inferred 7.6 3.8 0.85 0.94 208 CALVARIO Indicated – – – – – Inferred 0.1 0.0 0.53 – 2 TOTAL Indicated 14.9 2.9 1.20 1.37 576 Inferred 16.6 3.3 1.02 1.76 544 NOTES Refer to the full text of San Antonio Technical Report for the assumptions, qualifications and limitations relating to the San Antonio Gold Project and the San Antonio Technical Report. 1. Rodrigo Calles-Montijo, of Servicios Geológicos IMEx, S.C., William J. Lewis and Alan J San Martin, of Micon International Limited have reviewed and validated the mineral resource estimate for Sapuchi, Golfo de Oro, California, High Life and Calvario deposits. All are independent “Qualified Persons” (as defined in NI 43-101) responsible for the 2022 MRE Sapuchi. The effective date of the MRE Sapuchi is June 24th, 2022. 2. Specific extraction methods are used only to establish reasonable cut-off grades for various portions of the deposit. No Preliminary Economic Analysis, Pre-Feasibility Study or Feasibility Study has been completed to support economic viability and technical feasibility of exploiting any portion of the mineral resource, by any particular mining method. 3. The mineral resources disclosed were estimated using the Canadian Institute of Mining, Metallurgy and Petroleum (“CIM”) standards on mineral resources and reserves definitions, and guidelines prepared by the CIM standing committee on reserve definitions and adopted by the CIM council. 4. The calculated economic cut-off grade for the resource in: Oxides (70% recovery) is 0.27 g/t Au, transition and sulphides (90% recovery) is 0.44 g/t Au 5. Mineral resources are not mineral reserves and do not have demonstrated economic viability. 6. Geologic modeling was completed by Osisko Development. The MRE Sapuchi was completed by Geologist Leonardo Souza, MAusIMM (CP) of Talisker Exploration Services, under the supervision of Rodrigo Calles-Montijo, of Servicios Geológicos IMEx, S.C., William J.Lewis and Alan J. San Martin, of Micon International Limited 7. The estimate is reported for a potential open pit scenario and with USD assumptions. The cut-off grades were calculated using a gold price of $1,750 per ounce, a CAD:USD exchange rate of 1.3; mining cost of $2.95/t; processing cost of $4/t for oxides and $13.0/t for transition and sulphides; and general and administration costs of $2.50/t. The cut-off grades should be reevaluated in light of future prevailing market conditions (metal prices, exchange rate, mining cost, etc.). 8. A density of 2.55 g/cm3 was established for all oxide zones, 2.69 g/cm3 for transition zones and 2.74g/cm3 for the sulphide zones. 9. Resources for Sapuchi, Golfo de Oro, California, High Life and Calvario were estimated using Datamine Studio RM 1.3 software using hard boundaries on composited assays (3.0 m for all zones). Ordinary Kriging interpolation method was used in a with a parent block size = 10m x 10m x 5m. 10. Results are presented in-situ. Ounce (troy) = metric tons x grade / 31.10348. Calculations used metric units (metres, tonnes, g/t). The number of metric tons was rounded to the nearest thousand. Any discrepancies in the totals are due to rounding effects; rounding followed the recommendations as per NI 43-101.
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Gradient ODV NYSE TSXV osiskodev.com 2024 TRIXIE MINERAL RESOURCES ESTIMATE 48 DOMAIN CATEGORY TONNES GRADE (AU G/T) CONTAINED GOLD (OZ) GRADE (AG G/T) CONTAINED SILVER (OZ) T2 Measured 22,678 106.27 77,484 115.99 84,572 Indicated 11,939 23.19 8,902 51.07 19,602 M+I 34,617 77.62 86,387 93.60 104,173 Inferred 1,996 9.82 630 61.38 3,938 T3 Measured 2,385 9.46 725 75.34 5,776 Indicated 970 5.47 171 57.32 1,787 M+I 3,355 8.30 896 70.13 7,564 Inferred 139 6.27 28 63.14 282 T4 + Wild Cat + 40 FLT Measured 94,784 8.93 27,227 48.41 147,520 Indicated 51,827 6.48 10,795 37.59 62,637 M+I 146,611 8.07 38,023 44.58 210,156 Inferred 104,676 6.57 22,127 38.57 129,792 75-85 Measured – – – – – Indicated 60,008 12.93 24,943 80.95 156,185 M+I 60,008 12.93 24,943 80.95 156,185 Inferred 94,793 9.12 27,784 59.28 180,666 TOTAL Measured 119,847 27.36 105,437 61.73 237,868 Indicated 124,743 11.17 44,811 59.89 240,211 M+I 244,590 19.11 150,248 60.80 478,078 Inferred 201,603 7.80 50,569 48.55 314,678 NOTES 1. Effective date of the 2024 Trixie MRE is March 14, 2024. 2. Each of Mr. William Lewis, P.Geo., of Micon International Limited and Alan J. San Martin, MAusIMM(CP), of Micon International Limited (i) has reviewed and validated the 2024 Trixie MRE, (ii) is considered to be independent of the Company for purposes of Section 1.5 of NI 43-101, and (iii) is a "qualified person" within the meaning of NI 43-101. 3. The mineral resources were estimated using the Canadian Institute of Mining ("CIM"), Metallurgy and Petroleum's "CIM Definition Standards on Mineral Resources and Mineral Reserves" adopted by the CIM council. 4. Mineral resources are reported when they are within potentially mineable shapes derived from a stope optimizer algorithm, assuming an underground longhole stoping mining method with stopes of 6.1 m x 6.1 m x minimum 1.5 m dimensions. 5. Mineral resources that are not mineral reserves do not have demonstrated economic viability. 6. Geologic modelling was completed by Osisko Development modeling geologist Jody Laing, P.Geo, using Leapfrog Geo software. The 2024 Trixie MRE was completed by Osisko Development chief resource geologist, Daniel Downton, P.Geo using Datamine Studio RM 2.0 software. William Lewis and Alan J. San Martin of Micon International Limited independently reviewed and validated the mineral resource model. 7. The estimate is reported for an underground mining scenario and with USD assumptions. The cut-off grade of 4.32 g/t Au was calculated using a gold price of US$1,750/oz, a CAD:USD exchange rate of 1.30; total mining, processing and G&A costs of US$168.04/imperial ton; a refining cost of US$2.65/ounce; a combined royalty of 4.50%; and an average metallurgical gold recovery of 80%. 8. The stope optimizer algorithm evaluated the resources based on a gold equivalent grade which incorporates the silver grade estimate and assumes a silver price of US$23/oz and metallurgical silver recovery of 45%. 9. The 2024 Trixie MRE is comprised of six zones within the greater Trixie area: T2, T3, T4, Wild Cat, 40 Fault and 75-85. 10. Average bulk density values in the mineralized domains were assigned to the T2 (2.955 T/m3), T3 (2.638 T/m3), T4(2.618 T/m3), Wild Cat, and 40 Fault (2.621 T/m3), and 75-85 (2.617 T/m3) domains. 11. Inverse Distance Squared interpolation method was used with a parent block size of 1.2 m x 2.4 m x 2.4 m. 12. The 2024 Trixie MRE results are presented in-situ. Calculations used metric units (metres, tonnes, g/t). The number of tonnes is rounded to the nearest thousand. Any discrepancies in the totals are due to rounding effects. 13. Neither the Company nor Micon International Limited is aware of any known environmental, permitting, legal, title-related, taxation, socio-political, marketing or other relevant issue that could materially affect the mineral resource estimate other than disclosed in this news release. 14. Technical information differs from similar information made public by U.S. companies subject to the reporting and disclosure requirements of the U.S. Securities and Exchange Commission. Refer to "Cautionary Statement to U.S. Investors".
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