Osisko Metals Files Ni 43-101 Technical Report FOR the Gaspé Copper Project

OSISKO METALS FILES NI 43-101 TECHNICAL REPORT

FOR THE GASPÉ COPPER PROJECT

(Toronto, May 29, 2026) Osisko Metals Incorporated (the "Company" or "Osisko Metals") (TSX:

OM; OTCQX: OMZNF; FRANKFURT: OB51) is pleased to announce the filing on SEDAR+ of a

technical report titled "NI 43-101 Technical Report on the Gaspé Copper Project with an Updated

Mineral Resource Estimate for the Copper Mountain Deposit, Quebec, Canada" dated May 28,

2026 (with an effective date of January 17, 2026) (the "Technical Report "), in accordance with

National Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101").

The Technical Report was prepared by PLR Resources Inc. ("PLR"), G Mining Services Inc. ("G

Mining"), and Synectiq Inc. ( "Synectiq"), and supports the disclosure contained in the news

release of the Company dated April 14, 2026, titled " Osisko Metals Announces Significant

Increase in Mineral Resources at Gaspé Copper" (the "April News Release").

Pursuant to subsection 4.2(5)(b) of NI 43- 101, the Company confirms that there are no material

differences between the Technical Report and the April News Release. The mineral resource

estimates for all categories, including tonnages, grades (copper, molybdenum, silver, and copper

equivalent), contained metal, and all underlying technical parameters and assumptions, are

identical in the Technical Report and the April News Release. No reconciliation of differences is

required.

Updated Mineral Resource Estimate – Copper Mountain Deposit

The Technical Report presents the updated mineral resource estimate (the " 2026 MRE") for the

Copper Mountain deposit at the Gaspé Copper Project (the "Project"), located on the Gaspé

Peninsula of Eastern Québec, adjacent to the municipality of Murdochville. The 2026 MRE was

prepared by Pierre- Luc Richard, P.Geo., of PLR, with contributions from François Le Moal,

P.Eng., of G Mining for cut-off grade and pit shell optimization, and Christian Laroche, P.Eng., of

Synectiq for metallurgical parameters. All three qualified persons are "independent" of the

Company within the meaning of Section 1.5 of NI 43-101 (collectively, the "Qualified Persons").

The 2026 MRE, reported at a base- case cut-off grade of 0.16% copper equivalent ( "CuEq"), is

summarized in the table below(1).

Category Tonnes (Mt) CuEq (%) Cu (%) Mo (%) Ag (g/t) Cu (M lbs) Cu (kt) Mo (M lbs) Mo (kt) Ag (Moz)

Measured 136.5 0.42 0.37 0.014 1.98 1,128 512 41.9 19 8.7

Indicated 1,697.7 0.32 0.26 0.017 1.54 9,639 4,373 631.3 286.4 84.1

M&I 1,834.2 0.32 0.27 0.017 1.57 10,766 4,883 673.2 305.4 92.8

Inferred 238.8 0.46 0.41 0.016 1.88 2,158 979 82.9 37.6 14.5

Note:

(1) CuEq grades are presented for illustrative purposes only to express the combined value of copper,

molybdenum, and silver as a single copper grade. CuEq grades are calculated using long-term metal prices

of US$4.50/lb copper, US$20.00/lb molybdenum, and US$45.00/oz silver, and incorporate assumptions for

metallurgical recoveries (91% Cu, 72% Mo, 65% Ag), payable metal factors, smelting and refining charges,

transportation costs, and royalties. The CuEq calculation is essentially based on net smelter return ( NSR)

values and simplifies to: CuEq (%) = Cu (%) + 3.40327 × Mo (%) + 0.00008 × Ag (g/t). NSR cut -off of

US$11.71/t corresponds to the CuEq cut-off of 0.16%. Mineral resources are not mineral reserves and do

not have demonstrated economic viability. No eco nomic evaluation of these mineral resources has been

produced.

The quantity and grade of reported inferred mineral resources are uncertain in nature and there

has been insufficient drilling to define these inferred mineral resources as indicated mineral

resources. However, it is reasonably expected that the majority of inferred mineral resources

could be upgraded to indicated mineral resources with additional drilling. The Qualified Persons

are not aware of any known environmental, permitting, legal, title-related, taxation, socio-political,

financial, or other relevant issues that could materially affect the 2026 MRE. CIM definitions and

guidelines for mineral resource estimates have been followed. Resources are presented as

undiluted and in situ for an open- pit scenario and are constrained within a conceptual pit shell

developed using overall pit slopes of 48 degrees in bedrock and overburden. The 2026 MRE

model is based on 2,793 drill holes and 208,043 samples, including 159,212 metres in 238 drill

holes drilled by the Company between 2022 and 2025. Contained copper includes sulphide

copper only; soluble copper from surface oxidized zones was excluded. The pit optimization was

performed using Geovia Whittle 2022 software. Grade model resource estimation was calculated

using an ordinary kriging (OK) interpolation method in a sub- blocked model using blocks

measuring 15m × 15m × 15m in size and sub -blocks down to 1m × 1m × 1m. The measured

mineral resource , indicated mineral resource and inferred mineral resource categories are

constrained to areas where drill spacing is less than 60 metres, 120 metres, and 300 metres,

respectively, and show reasonable geological and grade continuity.

Previous Mineral Resource Estimates Superseded

The 2026 MRE supersedes all previously filed mineral resource estimates for the Copper

Mountain deposit, including the 2024 Q4 mineral resource estimate (with an effective date

November 4, 2024), the 2024 Q2 mineral resource estimate (with an effective date April 22, 2024),

and the 2022 mineral resource estimate (with an effective date April 12, 2022). These prior

mineral resource estimates should no longer be relied upon.

Qualified Persons and Data Verification

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

(i) Pierre-Luc Richard, P.Geo. (OGQ No. 1119), of PLR, a " qualified person" (as defined by NI

43-101) who is "independent" of the Company within the meaning of Section 1.5 of NI 43- 101,

and is responsible for Chapters 1 to 12 and 14 to 27 of the Technical Report, including the mineral

resource estimate; (ii) François Le Moal, P.Eng. (OIQ No. 6012262), of G Mining, a "qualified

person" (as defined by NI 43- 101) who is "independent" of the Company within the meaning of

Section 1.5 of NI 43-101, and is responsible for the pit optimization and cut-off grade parameters;

and (iii) Christian Laroche, P.Eng., of Synectiq, a "qualified person" (as defined by NI 43 -101)

who is "independent" of the Company within the meaning of Section 1.5 of NI 43- 10, and is

responsible for the metallurgical parameters.

The Qualified Persons have verified the data underlying the mineral resource estimate, including

sampling, analytical, and test data. Data verification included validation of the drill hole database,

review of sampling and assaying procedures, the QA/QC program, downhole survey

methodologies, and site visits conducted in January 2024 and August 2025. The Q ualified

Persons are of the opinion that the database is of good overall quality and suitable for mineral

resource estimation.

About the Gaspé Copper Project

The Gaspé Copper Project is located on the Gaspé Peninsula in eastern Quebec, approximately

825 km east of Montréal, adjacent to the municipality of Murdochville. The Property comprises

two mining concessions and 203 mining claims covering 11,407 hectares. All necessary support

infrastructure for the potential re- opening of the Project is already in place, including paved

highway access via Highway 198, port access at Sainte- Anne-des-Monts, and a Hydro-Québec

electrical substation on the property.

About Osisko Metals

Osisko Metals Incorporated is a Canadian exploration and development company creating value

in the critical metals sector, with a focus on copper and zinc. The Company acquired a 100%

interest in the past -producing Gaspé Copper mine from Glencore Canada Corporation in July

2023. Gaspé Copper hosts the largest undeveloped copper resource in eastern North America,

strategically located near existing infrastructure in the mining- friendly province of Québec. In

addition to the Gaspé Copper project, the Company is working with Appian Capital Advisory LLP

through the Pine Point Mining Limited joint venture to advance the Pine Point project in the

Northwest Territories. The Company is listed on the Toronto Stock Exchange under the trading

symbol "OM" and on the OTCQX under the symbol "OMZNE".

Cautionary Statement Regarding Mineral Resources

The mineral resources disclosed in this news release conform to standards and guidelines in NI

43-101 and were prepared by the Qualified Persons for purposes of NI 43- 101. The above-

mentioned mineral resources are not mineral reserves as they do not have demonstrated

economic viability. The quantity and grade of the reported inferred mineral resource estimate are

conceptual in nature and are estimated based on limited geological evidence and sampling.

Geological data is sufficient to imply but not verify geological grade and/or quality of continuity. It

is uncertain if further exploration will result in upgrading inferred mineral resources to a higher

category.

Cautionary Note Regarding Forward-Looking Information

This news release contains " forward-looking information" within the meaning of applicable

Canadian securities legislation based on expectations, estimates and projections as at the date

of this news release. Any statement that involves predictions, expectations, interpretations,

beliefs, plans, projections, objectives, assumptions, future events or performance (often, but not

always, using phrases such as "expects", or "does not expect ", "is expected" , "interpreted",

"management's view ", "anticipates" or "does not anticipate ", "plans", "budget", "scheduled",

"forecasts", "estimates", "potential", "feasibility", "believes" or "intends" or variations of such words

and phrases or stating that certain actions, events or results "may" or "could", "would", "might" or

"will" be taken, occur or be achieved) are not statements of historical fact and may be forward -

looking information and are intended to identify forward- looking information. This news release

contains forward-looking information pertaining to, among other things : the 2026 MRE and the

assumptions on which it is based, including long- term metal prices of US$4.50/lb copper,

US$20.00/lb molybdenum, and US$45.00/oz silver; estimated metallurgical recoveries of 92%,

70% and 70% for copper, molybdenum and silver, respectively; the Company 's plans for further

drilling Study; the estimated budget for the recommended work program; potential for resource

growth and category upgrades; assumptions about the ability to secure financing; timelines for

the 2026 drill program; the ability to advance Gaspé Copper to a construction decision (if at all);

the ability to increase the Company's trading liquidity and enhance its capital markets presence;

the potential re-rating of the Company; the ability for the Company to unlock the full potential of

its assets and achieve success; the ability for the Company to create value for its shareholders;

the advancement of the Pine Point project; and the anticipated resource expansion of the Gaspé

Copper system and Gaspé Copper hosting the largest undeveloped copper r esource in eastern

North America.

Forward-looking information is not a guarantee of future performance and is based upon a number

of estimates and assumptions of management, in light of management's experience and

perception of trends, current conditions and expected developments, as well as other factors that

management believes to be relevant and reasonable in the circumstances, including, without

limitation, assumptions about: the ability of exploration results, including drilling, to accurately

predict mineralization; errors in geologic al modelling; insufficient data; equity and debt capital

markets; future spot prices of copper, molybdenum and silver; the timing and results of exploration

and drilling programs; the accuracy of mineral resource estimates; production costs; political and

regulatory stability; the receipt of governmental and third party approvals; licenses and permits

being received on favourable terms; sustained labour stability; stability in financial and capital

markets; availability of mining equipment and positive relations with local communities and

groups. Forward -looking information involves risks, uncertainties and other factors that could

cause actual events, results, performance, prospects and opportunities to differ materially from

those expressed or implied by such forward-looking information. Factors that could cause actual

results to differ materially from such forward -looking information are set out in the Company's

public disclosure record on SEDAR+ (www.sedarplus.ca) under Osisko Metals' issuer profile.

Although the Company believes that the assumptions and factors used in preparing the forward-

looking information in this news release are reasonable, undue reliance should not be placed on

such information, which only applies as of the date of this news release, and no assurance can

be given that such events will occur in the disclosed time frames or at all. The Company disclaims

any intention or obligation to update or revise any forward-looking information, whether as a result

of new information, future events or otherwise, other than as required by law.

For Further Information

For further information on this news release, visit www.osiskometals.com or contact:

Don Njegovan, President

Email: [email protected]

Phone: (416) 500-4129