Osisko Mining : 2023 – Q4 – Management’s Discussion and Analysis

OSISKO MINING INC.

MANAGEMENT'S DISCUSSION AND ANALYSIS

FOR THE YEAR ENDED DECEMBER 31, 2023

This management's discussion and analysis (this "MD&A") reflects the assessment by management of the results and financial condition of Osisko Mining Inc. ("Osisko" or the "Corporation") and should be read in conjunction with the Corporation's unaudited interim financial statements for the year ended December 31, 2023 and 2022 and the notes thereto (the "Financial Statements"). Management is responsible for the preparation of the Financial Statements and this MD&A. The Financial Statements have been prepared in accordance with International Financial Reporting Standards ("IFRS") as issued by the International Accounting Standards Board (the "IASB"). This MD&A and the Financial Statements are available on SEDAR+ (www.sedarplus.ca) under Osisko's issuer profile and on Osisko's website (www.osiskomining.com).

This MD&A has been prepared as of March 4, 2024. All dollar figures in this MD&A are expressed in Canadian dollars unless stated otherwise.

DESCRIPTION OF BUSINESS

The Corporation was incorporated on February 26, 2010 and exists under the Business Corporations Act (Ontario). The Corporation's focus is the exploration and development of gold resource properties in Canada. Currently, the Corporation is exploring in Québec and looking for new opportunities to enhance shareholder value.

Exploration Strategy

Osisko's flagship project is the high-gradeworld-class Windfall Gold Deposit (the "Windfall Project") located between Val-d'Or and Chibougamau in Québec, Canada, in which Osisko beneficially owns a 50% interest and is being developed by Windfall Mining Group (the "Partnership"), a partnership formed between Osisko and Gold Fields with each of Osisko and Gold Fields holding a 50% interest in the Partnership. The Windfall Project is currently one of the highest-grade undeveloped gold projects in the world and is the highest-grade undeveloped gold project to be discovered in Québec. The Partnership holds a large area of claims totaling 223,379 hectares, mostly located in the Urban-Barry area and the Quévillon area.

The Corporation's strategy in partnership with Gold Fields is to advance and develop the Windfall Project towards a production decision while continuing to explore for additional deposits on the area of claims owned by the Partnership. Osisko completed and filed the Windfall Feasibility Study (as defined herein) on January 10, 2023 and completed an Environmental Impact Assessment for the Windfall Project (the "Windfall EIA") on March 29, 2023. The Corporation also signed a definitive agreement with Miyuukaa Corp. ("Miyuukaa"), a wholly-owned corporation of the Cree First Nation of Waswanipi ("CFNW"), for the construction of a proposed transmission line facilities and the transportation of hydroelectric power to the Windfall Project. The Partnership is advancing the Windfall Project towards mine permitting while advancing detailed engineering, Impact Benefit Agreement discussions, and procurement. Additional work such as conversion drilling, underground advancement towards a fourth bulk sample in the Lynx 4 Zone, and regional exploration programs continue to support the development plans for the Corporation. Drilling activities are ongoing at the Windfall Project, with infill drilling primarily in the Lynx Zones, and continuing the expansion of the deposit footprint through exploration holes.

UPDATES DURING THE YEAR AND SUBSEQUENT TO THE YEAR

Corporate Development and Acquisitions:

On January 18, 2024, Osisko announced grid power at the Windfall Project. The 85 km long 69 kV hydro-electric power line built, owned and operated by the CFNW was completed on schedule, and grid power had successfully been connected to the Windfall Project. The use of hydroelectricity at the Windfall Project marks the switching over from diesel generated electricity to operate the camp and underground infrastructure, which the Corporation anticipates will significantly reduce both power costs and greenhouse gas emissions at the site.

On December 28, 2023, Osisko announced that the Toronto Stock Exchange (the "TSX") had approved the Corporation's notice of intention to make a normal course issuer bid (the "NCIB Program"). Under the terms of the NCIB Program, Osisko may acquire up to 36,465,404 of its common shares ("Common Shares") from time to time in accordance with the normal course issuer bid procedures of the TSX.

On November 28, 2023, further to the binding letter agreement signed on September 25, 2023, Osisko executed a definitive earned-in and joint venture agreement (the "Earn-In Agreement") with Bonterra Resources Inc. (TSXV:BTR) ("Bonterra"), pursuant to which, among other things, Osisko was granted a 70% exploration earn-in right and joint venture on certain Urban- Barry properties held by Bonterra (hosting the Gladiator and Barry deposits), in addition to the adjoining Duke and Lac Barry properties, all located in Québec's Eeyou Istchee James Bay region (collectively, the "Phoenix Properties"). The Phoenix Properties total 496 claims over 22,508 hectares. Pursuant to the transaction, Osisko: (i) paid $1 million in cash to Bonterra upon entry into the binding agreement and an additional $4 million in cash to Bonterra upon the entry into the definitive

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agreement; and (ii) acquired the right to earn a 70% undivided interest in the Phoenix Properties upon funding $30 million in work expenditures on the Phoenix Properties over a three-year period.

On October 12, 2023, Osisko announced that the Partnership has concluded the hydro-electricity power allocation agreement with Hydro-Québec, a wholly-owned Crown corporation of the Québec Government, to meet the forecasted power demand for the Windfall Project.

On July 17, 2023, Québec's Ministry of Natural Resources and Forests lifted the access restriction to forests and roads on Crown land in the Eeyou Istchee James Bay area surrounding the Windfall site. To help and support provincial fire-fighting efforts, Windfall camp lodged over 100 firefighters from the Québec fire-fighting agency, Société de Protection des Forêts Contre le Feu, who were using the Corporation's facilities as a base to fight regional fires. The Corporation resumed underground drilling activities later in the week, and increased all other regular site activities back to normal levels as the local fire situation continued to improve.

The Corporation published its 2022 Sustainable Development Report on July 18, 2023, which provided a detailed synopsis of the environmental, social, and governance performance and economic contributions in the communities in which it operates. The 2022 Sustainable Development Report is available on Osisko's corporate website (https://www.osiskomining.com/data- center/).

On June 2, 2023 and 3, 2023, Québec's Ministry of Natural Resource and Forests announced prohibitions regarding forest access on Crown lands, and closed forestry roads for reasons of public safety, given the situation related to wildfires in the Abitibi and Eeyou Istchee James Bay regions. Osisko and the Partnership withdrew their respective employees until it was deemed safe to return to normal levels of activity in the region (see above).

On March 29, 2023, Osisko announced that it had submitted the Windfall EIA to the Environmental and Social Impact Review Committee (the "COMEX").

On March 16, 2023, Osisko announced that it had signed a definitive agreement with Miyuukaa with respect to the construction of proposed transmission facilities and the transport of hydroelectric power to the Windfall Project. The power line from the Waswanipi substation to the Windfall Project is located entirely on CFNW traditional lands covered by the James Bay and Northern Québec Agreement.

Financings:

On December 22, 2023, Osisko completed a "bought deal" non-brokered private placement of an aggregate of 2,481,390 "flow- through" Common Shares for aggregate gross proceeds of approximately $10.0 million.

On February 28, 2023, Osisko completed a "bought deal" brokered private placement financing of 32,260,000 units of the Corporation at a price of $3.10 per unit for aggregate gross proceeds of approximately $100 million (the "Unit Private Placement"). Each unit consists of one Common Share and one-half of one Common Share purchase warrant of the Corporation (each whole warrant, a "Warrant"). Each Warrant entitles the holder thereof to acquire one Common Share until August 28, 2024 at a price of $4.00 per Common Share, subject to customary anti-dilution adjustments.

On February 2, 2023, Osisko completed a "bought deal" non-brokered private placement of an aggregate of 4,568,051 "flow- through" Common Shares for aggregate gross proceeds of approximately $27.4 million.

Joint Venture on the Windfall Project:

On May 2, 2023, Osisko announced that it concluded a 50/50 joint venture with an affiliate of Gold Fields Limited ("Gold Fields") for the joint ownership and development of the Windfall Project (the "Transaction").

Transaction Highlights

The Transaction closed on May 2, 2023, with Gold Fields acquiring a 50% partnership interest in a partnership formed under the laws of the Province of Ontario, named "Windfall Mining Group". The Partnership has been formed to develop the Windfall Project and the surrounding Urban Barry and Quévillon, Québec exploration properties (collectively, the "Property"). The Transaction was implemented in accordance with, among other things, a framework agreement dated May 2, 2023 (the "Framework Agreement") among Osisko, Gold Fields, Gold Fields Holdings Company Limited, the Partnership and 1000516419 Ontario Inc., the manager of the Partnership (the "Manager"). Pursuant to the terms of the Framework

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Agreement, Gold Fields acquired 50% interest in the Partnership for an aggregate consideration of $600 million in cash to Osisko. The partnership agreement governing the Partnership also required Gold Fields to sole fund up to $75 million in contributions to the Partnership (half of which is on behalf of Osisko) for regional exploration in accordance with the terms described below. Prior to the acquisition of the 50% Partnership interest by Gold Fields, Osisko had contributed to the Partnership the Property together with any claims, permits, leases, all other real property, personal property, contractual rights and other assets currently held or acquired for the benefit of the Property.

Key highlights of the Transaction include:

• Gold Fields made an initial cash payment to Osisko of $300 million.
• Gold Fields has agreed to make an additional cash payment to Osisko of $300 million on issuance of the applicable permits authorizing the construction, operation and mining of the Windfall Project.
• Gold Fields will be required to sole fund expenditures for regional exploration up to a maximum of $75 million, after which regional exploration programs would be proportionately funded by each of Osisko and Gold Fields.
• Gold Fields was required to make two separate cash payments to Osisko totaling $34 million (the "Pre-Closing Paid Amounts").

1. 50% of the Pre-Closing Paid Amounts ($17 million) was paid to Osisko on July 31, 2023, and the remaining 50% was paid on December 31, 2023.

• 1. Pre-ClosingPaid Amounts represent Gold Field's share of the expenditures incurred by Osisko to advance the Windfall project from January 1, 2023.
• Gold Fields and Osisko will share all other project interim and construction costs on a 50/50 basis going forward.
• No cash taxes paid on proceeds to Osisko due to utilization of existing tax pools.
• Governance arrangements with equal representation in the Partnership from Osisko and Gold Fields, to leverage the skills, relationships and expertise of each party.

Exploration Highlights:

Drilling Highlights

During the year ended December 31, 2023, and subsequent to the year-end, Osisko provided several results from the ongoing drilling program with 143,601 metres drilled at the Windfall Project. Drill highlights include 286 g/t Au over 2.1 metres and 204 g/t Au over 2.0 metres at Triple Lynx on April 5, 20231 and 413 g/t Au over 8.0 metres and 632 g/t Au over 3.0 metres as announced on October 26, 2023.2

Regional Exploration Program

In 2023, Osisko engaged in a regional exploration program on the Urban-Barry gold project located in the Abitibi greenstone belt, Eeyou Istchee James Bay, Québec, which is presently held by the Partnership. The program is designed to explore areas outside the main Windfall gold deposit in the Urban-Barry volcanic belt. Near deposit exploration targets include a high potential area identified in the handing wall of the Bank Fault, 1.5 kilometres east northeast of the Lynx Zone of the Windfall Project. Pursuant to this regional exploration program, Osisko completed 16,141 metres in drilling.

Regional exploration activities also resumed on August 2, 2023 on the Quévillon Osborne Bell Project. A total of 5,892 metres of drilling was completed.

1. True width determinations are estimated at 55-80% of the reported core length intervals for most of the zones. The full set of drill results is available electronically on SEDAR+ (www.sedarplus.ca) under Osisko's issuer profile and Osisko's website (www.osiskomining.com).
2. Highlights from the 2023 drill program include 320 intercepts from 248 drill holes and 1 wedge. The highlights are intercepts with a metal factor (grams*meters) greater than 20. The intercepts are all located within the defined mineral resource estimate blocks as described in the Windfall Feasibility Study, a copy of which is available on SEDAR+ (www.sedarplus.ca) under Osisko's issuer profile, and have targeted upgrading (i) inferred mineral resources to measured or indicated mineral resources, and (ii) indicated minerals resources to measured mineral resources, as applicable.

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Subsequent to the year-end, Osisko has begun a 35,000 metre drill program on the Phoenix Properties as part of its 70% earn- in option with Bonterra. The program will initially focus on the Moss showing, located 5 kilometres south-west along strike from the Windfall Project. Regional exploration also continued on the Partnership's claim package with an additional 30,000 metres of drilling targeting potential gold-bearing structures including the extension of the Bank fault and porphyritic intrusions associated with favorable alterations.

Windfall Feasibility Study

On January 10, 2023, Osisko filed the Windfall Feasibility Study, which is available on SEDAR+ (www.sedarplus.ca) under Osisko's issuer profile. All figures in this section are on a 100%-project basis.

Windfall Feasibility Study Highlights*:

• Full-yearaverage production of 306,000 oz Au, 8.1 g/t Au average grade fully diluted
• Peak production of 374,000 oz Au in year two
• Average after-tax free cash flow of C$257 million per full year of production (C$2.3 billion cumulative free cash flow)
• Capex of US$607 million (includes US$38 million as contingency in direct and indirect costs), NPV/Capex ratio of 1.5
• All-insustaining cost ("AISC") of US$758/oz; cash cost of US$587/oz
• 3,400 tonne per day milling operation
• Average recovery of 93%; all-in mining cost of US$136/tonne
• C$6.2 billion of gross revenue
• Creation of over 1,000 direct and indirect jobs during construction and over 670 direct permanent jobs during operation

• Cautionary Statement: The reader is advised that the results of the Windfall Feasibility Study summarized in this MD&A are intended to provide only an initial, high-level overview of the Windfall Project potential and design options. The highlights are supported by the Windfall Feasibility Study. Reference should be made to the full text of the Windfall Feasibility Study for the assumptions, qualifications and limitations therein, a copy of which is available on SEDAR+ (www.sedarplus.com) under Osisko's issuer profile.

Notes:

1. The Windfall Feasibility Study mine plan and economic model include numerous assumptions. There is no guarantee the project economics described herein will be achieved.
2. Full years of production refer to Years 1 to 9.
3. AISC is presented within the meaning defined by the World Gold Council ("WGC"), less corporate G&A.
4. Total cash costs and cash costs per ounce, and AISC and AISC per ounce are non-IFRS financial measures. See "Non-IFRSFinancial Measures" for a discussion of non-IFRS financial measures.
5. References to C$ and US$ are to Canadian and United States dollars, respectively.

The Windfall Feasibility Study Details

The Windfall Feasibility Study was prepared by BBA Inc. under the supervision of Ms. Kim-Quyên Nguyên, P. Eng., MBA, Project Director of Osisko, and Osisko's technical team. The Windfall Feasibility Study was prepared in collaboration with the following firms: A2GC − Andrieux & Associates Geomechanics Consulting L.P. (Montréal, QC), BBA Inc. (Montréal, QC), GCM Consultants (Montréal, QC), Entech Mining Ltd. (Toronto, ON), PLR Resources Inc. (Montréal, QC) and WSP Canada Inc. (Montréal, QC). These firms provided mineral resource estimates, reserve estimates, design parameters, and cost estimates for mine operations, process facilities, major equipment selection, waste and tailings storage, reclamation, permitting, and operating and capital expenditures. Contributors and their areas of responsibility are summarized in the Windfall Feasibility Study. Project economics were evaluated based on a forecast date to receive the construction permit in Q1 2024. Unless stated otherwise, all costs are in Canadian dollars. All figures in this section are on a 100%-project basis.

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Table 1: FS Summary at US$1,600/oz Au

	Total mineralized material mined (t)	12,183,405
	Average mill feed diluted gold grade (Au g/t)	8.06
	Total gold contained (oz)	3,158,713
	Total gold produced (oz)	2,942 339
	Total gold payable (oz)	2,940,868
	Gold payable recovery (%)	93.1%
	Average annual gold produced (Au oz per year)	294,234
	Average mill feed diluted silver grade (Ag g/t)	4.18
	Silver payable recovery (%)	83.3%
	Total silver payable (oz)	1,366,537
	Total initial CAPEX (C$million)	788.6
	Sustaining capital (C$Million)	587.6
	Operating cost (per tonne milled)
	Mining (C$)	82.21
	Processing (C$)	40.76
	Waste & water management (C$)	6.30
	General & administration (C$)	32.81
	Electrical transmission line lease (C$)	14.59
	Total unit operating costs (per tonne milled) (C$)	176.67
	Table 2: Summary Economics at US$1,600 Au
	LOM net smelter return ("NSR") revenue (C$Million)	6,134
	Total LOM pre-tax cash flow (C$Million)	2,432
	Average annual pre-tax cash flow (C$Million)	243
	LOM income taxes (C$Million)	721.8
	Total LOM after-tax free cash (C$Million)	1,710.2
	Average annual after-tax free cash flow (C$Million)	171
	Discount rate (%)	5.0%
	Pre-tax NPV (C$Million)	1,685
	Pre-tax IRR	40.1%
	Pre-tax payback after start of production (years)	2.0
	After-tax NPV (C$Million)	1,168.4
	After-tax IRR	33.8%
	After-tax payback after start of production (years)	2.0
	Table 3: All-In Sustaining Costs
	Adjusted operating costs(2)
	Mining cost(1)	993.0
	Processing cost(1)	492.3
	Tailing & water management cost(1)	76.1
	General & administrative cost(1)	396.3
	Electrical transmission line lease cost(1)	176.2
	Royalties(1)	127.4
	Transport and refining costs(1)	20.0

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Ag by-product credit(1)	(37.3)
Adjusted operating costs(1)	2,244.1
Sustaining costs(2)
LOM sustaining costs(1)	587.6
Salvage value credit(1)	(18.7)
Reclamation and closure costs(1)	83.3
Total(1)	2,896.4
All-in sustaining costs (US$/oz)	757.6
All-in sustaining costs (C$/oz)	984.9

Notes:

1. All-insustaining costs are presented as defined by the WGC less corporate G&A.
2. Millions of Canadian dollars.

Sensitivities are described in the Windfall Feasibility Study.

The mineral reserve estimate is based on Windfall MRE (as defined herein). The Windfall MRE is described below in Section 2 - "Mineral Resources and Mineral Reserves" of this MD&A. The mineral reserve estimate on which the Windfall Feasibility Study is based was completed by Patrick Langlais (P.Eng.) of Entech Mining Ltd. (summarized below in Table 4) and consists of probable reserves using a 3.5 g/t operating, 2.5 g/t incremental, and 1.7 g/t development cut-off grade.

Table 4: Windfall Mineral Reserve Estimate (1)

										Probable
	Area			Tonnes			Grade			Grade		Ounces Au			Ounces Ag
			(000 t)			Au (g/t)			Ag (g/t)		(000 oz)			(000 oz)
	Lynx(2)	8,882		8.83		4.58		2,523		1,307
	Underdog	906		6.80		2.31		198		67
	Main(3)	2,363		5.55		3.44		422		261
	Total in situ	12,151		8.04		4.19		3,143		1,635
	Stockpiles	33		15.24		3.74		16		4
	Total	12,183		8.06		4.18		3,159		1,639

Notes:

1. See the Windfall Mineral Reserve Estimate notes below under the heading "2. Mineral Resources and Mineral Reserves".
2. Lynx area includes: Lynx Main, Lynx HW, Lynx SW, Lynx 4, and Triple Lynx.
3. Main area includes: Zone 27, Caribou 1, Caribou 2, Caribou Extension, Bobcat, Mallard, Windfall North, and F-Zones.

Capital and Operating Costs Estimate

The overall capital cost estimate developed in the Windfall Feasibility Study generally meets the AACE Class 3 requirements and has an accuracy range of between -10% and +15%. Contingency was calculated based on Monte Carlo simulation, using a P50 value. All figures in this section are on a 100%-project basis.

Table 5: Capital Cost Summary (1)(2)

Capital costs (millions of Canadian dollars)	Pre-Production		Sustaining	Total
Mining	80.2	556.7	636.9
Mineral processing and filtration plant	273.8	0.0	273.8
Mine surface facilities	0.0	3.7	3.7
Electrical and communication	14.7	0.0	14.7
Plant surface facilities	63.9	0.0	63.9
Tailings and water management	69.5	26.0	95.5
Indirect and owner's costs	237.0	1.3	238.3
Site reclamation and closure restoration	0.0	83.3	83.3
Salvage value	0.0		(18.7)	(18.7)

Subtotal

739.1

652.3

1 391.3

Contingency (P50)

49.5

0.0

49,5

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Notes:

Capital costs (millions of Canadian dollars)	Pre-Production	Sustaining	Total
Total capital costs(2)	788.6	652.3	1 440.8
Production revenue NSR		6 134.3	6 134.3

1. Totals may differ due to rounding.
2. Total capital costs exclude: (i) sunk costs for pre-ordered grinding mills (C$5.6 million) and EIA (C$1.1 million); (ii) long-lead items, including engineering studies (C$34.6 million), logistics and warehousing (C$2.1 million), mechanical and electrical packages (C$57.0 million), camp (C$32.2 million), material opportunity purchase (C$8 million), mining fixed equipment (C$2.9 million) and contingency (C$3.0 million).

Table 6: Operating Cost Summary

Mining

Operating Costs (millions of Canadian dollars)
Mining	993.0
Processing	492.3
Waste and water management	76.1
General & administration	396.3
Electrical transmission line lease	176.2
Total operating costs	2 134.0

The mineral resources used in the mine plan are contained in three different zones over a strike length of 2,300 metres and span from the surface to a depth of approximately 1,100 metres. Each zone is characterized by multiple tabular panels, which mainly trend ENE and dip vertically to sub-vertically.

The planned underground mine will have a targeted production rate of 3,400 tonnes per day ("tpd"). The selected mining method is longitudinal longhole open stoping. Stope dimensions are 20 metres in height, a median of 25 metres in strike length, and have a median thickness of 4.4 metres with a minimum thickness of 3.0 metres. Mineralized material will be extracted using a fleet of 14 and 18-tonneload-haul-dumps and 54-tonne haul trucks using a ramp to surface.

Processing

A total of 3,400 tpd run-of-mine will be processed at the Windfall site. The process plant consists of primary crushing, followed by a grinding circuit consisting of a SAG mill (24' x 11', in a closed circuit with a pebble crusher) and a ball mill (17' x 31', in a closed circuit with cyclones - SABC circuit). A gravity circuit followed by leaching recovers coarse gold from the cyclone underflow, while the cyclone overflow, at a P80= 37 microns, is treated in a carbon-in-pulp circuit, followed by SO2/air cyanide destruction. Gold and silver are recovered in an adsorption-desorption-recovery circuit and electrowinning cells, with gold room recovery and production of doré bars. The process plant is followed by a tailings filtration plant with a filter press to produce paste backfill to send underground and/or dry material for filtered tailings stack storage.

Information on surface infrastructure and indirect costs, environment and closure, stakeholder engagement, and royalties are detailed in the Windfall Feasibility Study.

Environmental Impact Assessment

On March 29, 2023, Osisko announced that it has submitted the Windfall EIA to the COMEX. Upon completion of the project review, the COMEX is expected to issue a recommendation to the Deputy Minister of Québec's Ministère de l'Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs. Should a positive recommendation be granted by the COMEX, the Deputy Minister would then issue a Certificate of Authorization pursuant to section 164 of Québec's Environment Quality Act for the Windfall Project. The issuance of such Certificate of Authorization is a pre-condition to the Partnership applying for the other authorizations required to begin the construction and operations at the Windfall site.

On August 25, 2023, the COMEX issued a letter requesting additional studies, an addendum to the EIA was submitted on December 21, 2023. The Windfall EIA review process by the COMEX is following its course and the Corporation is expecting that the Partnership will receive the first round of follow-up questions in the coming months. In parallel, the Corporation expects to finalize the Impact and Benefit Agreement with the CFNW and the Cree Nation Government in 2024.

The Windfall EIA and its addendum covers 26 fields of study from impacts on water, air, and vegetation to impacts on regional and provincial economies. The following represents some of the highlights(1) of the Windfall EIA as related to benefits to local communities and governments:

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• Robust water management planning using a state-of-the-art water treatment plant integrated into the proposed future development plan.
• A tailings management facility designed to the highest modern industry standards.
• $3.5 billion of investments(2) for construction, sustaining costs and operations by 2035, with an additional $83 million reserved for future closure costs.
• $2.3 billion of contribution to Québec's GDP by 2035.
• An estimated $712 million (including mining duties) gross provincial tax revenues for Québec, and $333 million gross federal tax revenues by 2035.(3)
• An estimated $68 million in local property taxes and school tax revenues by 2035.

Notes:

1. Economic and fiscal impacts including contribution to Québec's GDP were determined by Aviseo Conseil by applying EcoTec's cross-sector(input-output) model. Estimation of corporate income tax, mining duties, local property and school tax were estimated based on the Windfall Feasibility Study. All monetary amounts are reported in Canadian dollars. Details about methodology or main hypothesis are described in the Windfall EIA and are based on the Windfall Feasibility Study.
2. The cumulative $3.5 billion of investments includes initial CAPEX of $788 million, sustaining CAPEX of $588 million and cumulative operation costs over LOM of $2,134 million based on the Windfall Feasibility Study.
3. Gross provincial tax estimated contributions include workers' personal income taxes, health services funds and sales taxes while gross federal tax contributions include workers' personal income taxes.

Overall Performance:

During the year ended December 31, 2023, the Corporation had approximately $15.2 million of exploration and evaluation expenditures, and $15.6 million of property, plant and equipment expenditures. In the same period, the Partnership had approximately $74.8 million of exploration and evaluation expenditures, and $51.3 million of property, plant and equipment expenditures. In the same period, the Corporation incurred $21.0 million on general and administration expenses (including salaries and benefits).

The Corporation has completed, as of May 2, 2023, its surface drill program that began in 2015 and evolved in scope over time, resulting in Osisko completing: (i) 1,869,441 metres of drilling on the Windfall Project; (ii) 105,147 metres of drilling on the Urban-Barry Project; and (iii) 76,373 metres of drilling on the Quévillon Osborne-Bell property, for a combined total drilling campaign of 2,050,961 metres.

The Partnership has completed, since May 2, 2023, an additional: (i) 77,682 metres of drilling on the Windfall Project; (ii) 1,778 metres of drilling on the Urban-Barry Project; and (iii) 5,892 metres on Quévillon, for a combined total drilling campaign of 85,352 metres during the period commencing on May 2, 2023 and ending on December 31, 2023. The slowdown in drilling for the year ended December 31, 2023 is mainly due to the forest fires that took place on June 5, 2023 and lasted until July 17, 2023. Management believes these fundamental elements provide a robust base necessary to build a mining company that could generate value for its shareholders over time. See the tables in Section 2 - "Mineral Resources and Mineral Reserves" of this MD&A for the grade and quantity of each category of mineral resources and mineral reserves included in the foregoing disclosure.

Several other milestones have been reached at the Windfall Project during the year ended December 31, 2023, including the release of the Windfall Feasibility Study, a definitive agreement with Miyuukaa for the delivery of hydroelectric power to the Windfall Project, a power agreement with Hydro Québec for the allocation for the electrical Installation of 27,400 kW power demand, an earn-in agreement with Bonterra and the submission of the Windfall EIA. During the year ended December 31, 2023, the exploration ramp was slowed down as the Corporation and the Partnership worked on detailed engineering and completion of construction projects underground. The total advancement of the exploration ramp is now at 12,479 metres.

As of December 31, 2023, the Lynx underground exploration ramp was at a vertical depth of approximately 640 metres below surface. Osisko and the Partnership continue to advance underground infrastructure at the Windfall Project. A series of ventilation raises and secondary egress from surface down to the 580-metre level were completed. In addition, installation of long-term evolution (LTE) infrastructure has commenced underground, and construction of a new pumping station was completed on the 460-metre level.

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1. SUMMARY OF MINERAL PROPERTIES

The Corporation's gold mineral properties in Canada are summarized below:

Notes:

Continuing Exploration Properties	Location	Status
Windfall	Québec	Owned 50%(1)
Quévillon Osborne-Bell	Québec	Owned 50%(1)
Urban-Barry	Québec	Owned 50%(1)
Blondeau-Guillet	Québec	Owned 100%(2)
Phoenix	Québec	Earn-in 70%(4)
Urban Duke	Québec	Owned 30%(3)

1. Represented by a 50% interest in the Partnership. Prior to the completion of the Transaction on May 2, 2023, this property was 100% owned by Osisko.
2. Vior Inc. ("Vior") has entered into an earn-in right to acquire up to 75% interest on the property on August 24, 2021.
3. Bonterra has an earn-in right of 70% on the property which was executed on July 12, 2021 (subject to the below).
4. Osisko has an earn-in right for 70% of the Phoenix Properties (which, for the avoidance of doubt, includes Urban Duke).

2. MINERAL RESOURCES AND MINERAL RESERVES

Windfall Mineral Resource Estimate

On January 10, 2023, Osisko filed the Windfall Feasibility Study. The Windfall mineral resource estimate, which has an effective date of the June 7, 2022 (the "Windfall MRE") shown in Table 8, is included in the Windfall Feasibility Study. The Windfall MRE uses a base cut-off of 3.5 g/t Au in the measured mineral resource, indicated mineral resource and inferred mineral resource categories. The Windfall MRE is reported inclusive of the mineral reserve estimate. Mineral resources are not mineral reserves as they have not demonstrated economic viability. All figures in this section (including information in the tables below) are on a 100%-project basis.

Highlights:

• 4.1 M oz Au measured & indicated ("M&I") resource averaging 11.4 g/t Au.*
• M&I resource ounces increase of 26% (0.8 M oz Au).*
• M&I resource grade increase of 8%.*
• Lynx contains 65% of MRE total (M&I 3.1 M oz averaging 13.0 g/t Au; inferred 1.7 M oz averaging 10.8 g/t Au).*
• 50% of the Windfall MRE is hosted in 26 wireframes; 75% of the Windfall MRE is hosted in 97 wireframes.
• 98% of the Windfall MRE is located from surface to 1,200 metres vertical depth.
• • See Table 8 (entitled "The Windfall MRE by Area (3.5 g/t Au cut-off)") for a complete breakdown of the measured mineral resources and indicated mineral resources comprising the M&I figures presented herein.

Table 7: Windfall MRE Sensitivity Table

Cut-off			Measured + Indicated				Inferred
Grade					Ounces			Grade		Ounces
(g/t Au)	Tonnes	Gold	Grade	Gold	Ag	Tonnes	Gold	Ag	Gold	Ag
	(000 t)	(g/t)	Ag (g/t)	(000 oz)	(000 oz)	(000 t)	(g/t)	(g/t)	(000 oz)	(000 oz)
5.00	8,213	13.9	7.0	3,667	1,854	7,986	10.7	6.0	2,760	1,545
4.50	9,029	13.1	6.7	3,791	1,935	9,078	10.0	5.6	2,927	1,638
4.00	9,950	12.2	6.3	3,917	2,020	10,561	9.2	5.2	3,129	1,754
3.50	11,061	11.4	5.9	4,050	2,114	12,287	8.4	4.8	3,337	1,892
3.00	12,388	10.5	5.6	4,188	2,217	14,299	7.7	4.4	3,547	2,033

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