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Osisko Development Reports First Quarter 2026 Results

Financials

ODV NYSE TSXV News Release

www.osiskodev.com Page 1 of 10

OSISKO DEVELOPMENT REPORTS FIRST QUARTER 2026 RESULTS

(All dollar amounts are expressed in Canadian dollars, unless stated otherwise)

Montreal, Québec, May 11, 2026 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV) ("Osisko

Development" or the "Company") reports its financial and operating results for the three months

ended March 31, 2026 ("Q1 2026").

Q1 2026 HIGHLIGHTS

Operating, Financial and Corporate Updates:

• As of March 31, 2026, the Company had approximately $ 594.3 million in cash and cash

equivalents. Approximately $153.2 million (US$109.9 million), inclusive of accrued interest, is

outstanding under the initial draw of the US$450 million senior secured project loan credit facility

(the " 2025 Financing Facility") with funds advised by Appian Capital Advisory Limited

("Appian") for the development and construction of the Cariboo Gold Project.

• $2.2 million in revenues ( nil in Q1 2025) and $ 0.7 million in cost of sales ( nil in Q1 2025)

generated from the sale of 270 gold ounces from small-scale activities including heap leaching

of certain tailings and stockpile material and direct shipping of mineralized material at the Tintic

Project, generating an operating loss of $9.7 million ($40.8 million loss in Q1 2025).

• On January 22, 2026, a contractor working on surface activities suffered a fatal injury following

an isolated incident at the Cariboo Gold Project. The Company promptly notified appropriate

authorities, and an investigation of the incident was initiated. Activities at the project site were

temporarily suspended to allo w for completion of an investigation. On March 2, 2026,

resumption of planned site activities was announced, following the successful implementation of

a phased gradual reopening plan of surfa ce and underground activities over several preceding

weeks, in coordination with and approval from the relevant regulatory authorities , and with a

focus on ensuring the health and safety of all employees and contractors.

• On January 27, 2026, the Company completed the previously announced sale of its 100%

interest in the San Antonio Gold Project located in Sonora State, Mexico, to Axo Copper Corp.

through the sale of Sapuchi Minera.

• On February 2, 2026, the Company appointed Ms. Sarah Harrison as Vice President, Permitting

HIGHLIGHTS

Q1 2026 (at March 31, 2026)

 Financial: ~$594.3 million in cash and cash equivalents; sold 270 ounces of gold from small-scale mining

activities at the Tintic Project; received ~$36.5 million in proceeds from warrant exercises

 Financing: Completed a prospectus offering of common shares for ~US$143.8 million in gross proceeds

 Cariboo Gold Project: Resumed planned site activities under a phased reopening plan following a

temporary suspension due to a fatal incident that occurred on January 22, 2026; entered into a project and

construction management services agreement with JDS Energy & Mining; released new infill drill results

from the Lowhee Zone (100% of planned drilling now complete, while final assays and reconciliation results

remain pending); 11 drill rigs operating at site across various infill and exploration programs

 Corporate: Completed the sale of the San Antonio Gold Project; appointed Sarah Harrison as VP, Permitting

& Compliance; announced the Company's inclusion in the VanEck Junior Gold Miners ETF (GDXJ)

Subsequent to Q1 2026

 Corporate: Granted incentive awards; appointed Sarah MacDonald as VP, Construction Contracting and

Commercial

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and Compliance.

• On February 3, 2026, the Company completed its previously announced (on January 26, 2026)

prospectus offering of common shares of the Company , issuing an aggregate of 40,607,650

common shares at a price of US$3.54 per common share for aggregate gross proceeds of

US$143.8 million ($196.3 million).

• On February 9, 2026, the Company entered into a definitive Project and Construction

Management Services Agreement with JDS Energy & Mining Inc. for the development of the

Cariboo Gold Project.

• On March 9, 2026, the Company announced receipt of approximately $24.9 million from the

exercise of 5,625,031 common share purchase warrants of the Company, held by certain funds

advised by Appian Capital Advisory Limited. Together with other warrant exercises during Q1

2026, the Company received aggregate proceeds of $36.5 million from warrant exercises.

• On March 16, 2026, the Company announced inclusion in the VanEck Junior Gold Miners ETF

("GDXJ") announced on March 13, 2026, which became effective at the close of markets on

March 20, 2026.

• On March 27, 2026, Osisko Development's Board of Directors approved certain minor

administrative amendments to the Company's omnibus equity incentive plan to facilitate plan

administration. The omnibus incentive plan was last approved by shareholders on May 7, 2025.

In accordance with the terms of the omnibus equity incentive plan and applicable TSX Venture

Exchange policies, shareholder approval is not required for these amendments. The amended

omnibus equity incentive plan remains subject to final acceptance by the TSX Venture Exchange.

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

• Infill Drilling Program . The 13,000-metre infill drill program within the Lowhee Zone was

undertaken as part of the Appian 2025 Financing Facility obligations.

o A total of 13,684 metres of drilling has been completed, representing 100% of the

planned program, of which 11,025 metres have been released with assays. Assay results

and associated quality assurance and quality control reviews are pending for unreleased

holes. The Company anticipates finalizing the results for the program in the second

quarter of 2026.

• Pre-Construction Activities. The Company continues to advance pre-construction activities,

including certain surface infrastructure and underground development.

o Water treatment plant: Upgrades to the Bonanza Ledge water treatment plant are in

the final commissioning stages, with full operation expected in the second quarter of

2026.

o Underground development: To date, approximately 2.1 km of underground

development has been completed from the existing Cow Portal into the Lowhee Zone,

and along the main access ramp, through the Lowhee fault, towards the Cow Mountain

Zone. Development progress has been below plan while encountering challenging

ground conditions in and around the Lowhee fault, requiring enhanced ground support.

Development rates are expected to improve as the ramp advances beyond this zone.

The raisebore pad for the first underground ventilation raise started in Q1 2026.

o Surface infrastructure: Construction of the waste rock storage facility, the sediment

control pond, and other critical infrastructure continues. Early works, including tree

clearing and geotechnical drilling, commenced in Q1 2026 at the mine site complex,

where the primary processing facility will be located.

o Camp upgrade: The site camp upgrade and expansion to 266 rooms is complete and,

together with other Company -controlled accommodation s, is expected to provide

capacity aligned with peak construction manpower requirements.

• Exploration & Conversion Drilling Programs. A multi-faceted exploration drilling campaign

across the Cariboo Gold Project and regional targets is underway. Together with planned infill

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drilling that has the objective of upgrading inferred mineral resources to higher confidence

categories, up to 20 drill rigs are expected to be active at times throughout 2026, as the various

programs overlap and advance , representing up to approximately 160,000 metres of planned

drilling across all targets. Eleven drill rigs are currently operating across all programs.

o Eight drill rigs are currently operating on two surface exploration programs, including

four surface drill rigs targeting potential mineralization below the current extent of the

Cariboo Gold Project deposit to depths of up to 1,000 metr es. To date, approximately

10,600 metres of drilling have been completed, with assays pending.

o A second surface exploration program on the adjacent Proserpine regional target has

ramped up to four drill rigs, with approximately 5,750 metres completed to date.

o Infill and conversion drilling is planned in 2026 with the objective of upgrading inferred

mineral resources to higher confidence resource categories and potentially into mineral

reserves, after considering applicable modifying factors . The initial targets are within

and below the current Cariboo Gold deposit.

Figure 1: Waste rock storage facility (WRSF) aerial overview of ongoing works.

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Figure 2: Sediment control pond (SCP) installed liner and placement of aggregates.

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Figure 3: BL water treatment plant commissioning (legacy and expansion).

Figure 4: Mine site complex processing facility site preparation works.

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Figure 5: Lowhee Zone ventilation raise bore.

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

• Small-Scale Heap Leach Project and Selective Mining . In the quarter , the Company

continued small-scale heap leaching and direct shipping of mineralized material which generated

sales of 270 ounces of gold. Test mining continued in Q1 2026, with approximately 2,000 tonnes

of higher-grade mineralized material stockpiled for direct shipping to a purchaser. Test mining

is anticipated to continue in Q2 2026.

• While management continues to evaluate options for the next steps at the Tintic Project, it is

expected that limited activities beyond care and maintenance may occur on the Tintic Project

from time to time, including any additional direct shipping of mineralized material from the Trixie

test mine.

2026 OBJECTIVES

Activity

Expected Timing

of Completion(2)

Anticipated

2026 Cost(1)

Cariboo Gold Project

Underground Development (including production drilling) Q4 2026 $39.5 million

Regional surface exploration drilling Q4 2026 $3.7 million

Mine design, processing, water management, infrastructure and other Q4 2026 $14.7 million

Underground Infill Drilling to Convert Mineral Resources to Mineral Reserves Q4 2026 $4.4 million

Surface (Directional) Drilling to expand Mineral Resource Estimate at depth (up to

300 metres below current Mineral Resource Estimate) Q4 2026 $1.7 million

Surface Drilling to expand geology and mineralization at depth (+700 metres

below surface) Q4 2026 $3.9 million

Note:

(1) The expenditures disclosed in this table include amounts approved by the Board of Directors as at March 31, 2026, net of

amounts already incurred during the first quarter of 2026. Additional expenditures will be required to complete certain of th e

objectives and are subject to approval by the Board of Directors.

(2) For the portion of activities to be incurred in 2026.

SUBSEQUENT TO Q1 2026

• On April 1, 2026, the Company granted an aggregate of (i ) 1,104,400 stock options of the

Company (the "Options"), and (ii) 1,426,600 restricted share units of the Company (" RSUs")

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to certain senior officers and non-executive employees (collectively, the "Incentive Awards"),

pursuant to the Company's omnibus equity incentive plan.

• On May 4, 2026, the Company appointed Ms. Sarah MacDonald as Vice President, Construction

Contracting and Commercial.

Consolidated Financial Statements

The Company's unaudited condensed interim consolidated financial statements (the " Financial

Statements") and related management's discussion and analysis (" MD&A") for the three months

ended March 31, 2026 have been filed with Canadian securities regulatory authorities and the U.S.

Securities and Exchange Commission. These filings are available on the Company's website at

www.osiskodev.com, on SEDAR+ (www.sedarplus.ca) and on EDGAR (www.sec.gov) under Osisk o

Development's issuer profile.

Qualified Persons

The scientific, geological and technical information in this news release has been reviewed and approved

by Scott Smith, P. Geo., Vice President, Exploration of Osisko Development , who is considered a

"qualified person" within the meaning of National Instrument 43 -101 – Standards of Disclosure for

Mineral Projects ("NI 43-101").

Technical Reports

Scientific and technical information relating to the Cariboo Gold Project and the 2025 Feasibility Study

on the Cariboo Gold Project 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").

Scientific and technical i nformation relating to the Tintic Project and the current mineral resource

estimate for the Trixie deposit (the "2024 Trixie MRE") is supported by the technical report titled "NI

43-101 Technical Report, Mineral Resource Estimate for the Trixie Deposit, Tintic Project, Utah, United

States of America " and dated April 25, 2024 (with an effective date of March 14, 2024) (the "Tintic

Technical Report" and, together with the Cariboo Technical Report, the "Technical Reports").

For readers to fully understand the information in the Technical Reports, reference should be made to

the full text of the Technical Reports in their entirety, including all assumptions, parameters,

qualifications, limitations and methods therein. The Technical Reports are intended to be read as a

whole, and sections should not be read or relied upon out of context. The Technical Reports were

prepared in accordance with NI 43-101 and are 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.

ABOUT OSISKO DEVELOPMENT CORP.

Osisko Development Corp. is a continental North American gold development company focused on past

producing mining camps with district -scale potential. The Company's objective is to become an

intermediate gold producer through the development of its flagship, fully permitted, 100% -owned

Cariboo Gold Project, located in central British Columbia, Canada. Its project pipeline is complemented

by the Tintic Project located in the historic East Tintic mining district in Utah, U.S.A., a brownfield

property with si gnificant exploration potential, extensive historical mining data, and access to

established infrastructure. Osisko Development is focused on developing long -life mining assets in

mining-friendly jurisdictions while maintaining a disciplined approach to capital allocation, development

risk management, and mineral inventory growth.

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

Sean Roosen Philip Rabenok

Chairman and CEO Vice President, Investor Relations

Email: [email protected] Email: [email protected]

Tel: +1 (514) 940-0685 Tel: +1 (437) 423-3644

www.osiskodev.com Page 8 of 10

CAUTIONARY STATEMENTS

Cautionary Statement Regarding Financing Risks

The Company's development and exploration activities are subject to financing risks. A s of the date hereof , the Company has

exploration and development assets which may generate periodic revenues through test mining but has no mines in the commercial

production stage that generate positive cash flows. The Company cautions that test mining at its operations could be suspende d at

any time. The Company's ability to explore for and discover potential economic projects, and t hen to bring them into production, is

highly dependent upon its ability to raise equity and debt capital in the financial markets. Any projects that the Company de velops

will require significant capital expenditures. To obtain such funds, the Company may sell additional securities including, but not limited

to, the Company's shares or some form of convertible security, the effect of which may result in a substantial dilution of th e equity

interests of the Company's shareholders. Alternatively, the Company may also sell a part of its interest in an asset in order to raise

capital. There is no assurance that the Company will be able to raise the funds required to continue its exploration programs and

finance the development of any potentially economic deposit that is identified on acceptable terms or at all. The failure to obtain the

necessary financing(s) could have a material adverse effect on the Company's growth strategy, results of operations, financia l

condition and project scheduling.

Cautionary Statement Regarding Test Mining Not Supported by a Feasibility Study

Certain operations of the Company including prior test mining activities at the Tintic Project's Trixie test mine, have operated without

the benefit of a feasibility study including 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 Comp any

cautions that historically, such projects have a much higher risk of economic and technical failure. There is n o guarantee that

commercial production will commence, continue as anticipated or at all or that anticipated production costs will be achieved. The

failure to commence or continue production could 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 could have a material adverse impact on the

Company's cash flow and potential profitability.

Cautionary Statement to U.S. Investors

As a foreign private issuer under U.S. securities laws that files reports under the Canada -U.S. multijurisdictional disclosure system,

the Company is permitted to prepare and report information regarding mineral properties, mineralization and estimates of mineral

reserves and mineral resources, including the information in its technical reports, financial statements and MD&A, in accordance with

Canadian reporting requirements, which are governed by NI 43 -101. As such, such information concerning mineral pro perties,

mineralization and estimates of mineral reserves and mineral resources, including the information in its technical reports, f inancial

statements and MD&A, is not comparable to similar information made public by most companies subject to U.S. miner al property

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 S tandards"), 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 descri bed 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 economic ally 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 economic ally.

Therefore, U.S. investors are also cautioned not to assume that all or any part of the "inferred mineral resources" exist. 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. While the above te rms 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 minera l 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.

Risks related to the development of the Cariboo Gold Project

The development of a new mining operation, including the construction of processing facilities, tailings storage infrastructu re, access

roads, power supply and other supporting infrastructure, is a complex and costly undertaking. The Cariboo Gold Project r emains in

the development stage and there is no certainty that it will be brought into commercial production within anticipated timelin es, at

anticipated costs, or at all. The results of the Cariboo Technical Report are based on a number of assumptions, in cluding, among

others, geological interpretations, estimated mineral resources and mineral reserves, metallurgical recoveries, construction schedules,

capital and operating costs, labour and equipment availability, transportation and energy costs, regulato ry requirements, and

projected commodity prices. These assumptions are inherently uncertain and may prove to be inaccurate.

Actual results, costs and development timelines may differ materially from those currently anticipated due to factors such as :

unforeseen geological conditions; changes to mine plan optimization; equipment failures; shortages of skilled labour and contractors;

increases in the cost of materials, equipment or energy; design modifications; delays related to permitting or receipt of gov ernment

approvals; adverse weather or climate conditions; and community and/or Indigenous opposition. In addition, the develop ment of

mining projects often requires substantial capital expenditures, and delays or cost overruns may require the Company to seek

additional financing, which may not be available on favorable terms or at all. If the Company is unable to complete constru ction and

development of the Cariboo Gold Project on a timely and cost-effective basis, or if operating performance following commissioning is

materially lower than expected, the project may fail to achieve anticipated economic results. Any such events cou ld have a material

adverse effect on the Company's business, financial condition and results of operations.