Includes 28.5 Metres Averaging 2.31% Cu and 11.8 g/t Ag

South-Western Extension provides additional high-grade intercept of 86 metres averaging 1.36% Cu

MONTREAL, Sept. 28, 2026 (GLOBE NEWSWIRE) -- Osisko Metals Incorporated (the “Company” or “OsiskoMetals”) (TSX: OM; OTCQX: OMZNF; FRANKFURT: 0B51) is pleased to announce additional new analytical results from the 2026 drill program at the Gaspé Copper Project, located in the Gaspé Peninsula of Eastern Québec.

New results are presented below (see Table 1), including 28 mineralized intercepts from 12 drill holes. Reported “infill” intercepts are located within the 2026 MRE model (see April 14, 2026 news release), focused on upgrading Inferred Mineral Resources to Measured or Indicated categories, as applicable. “Expansion” intercepts are located outside the 2026 MRE model and comprise either i) in-pit expansion, which offers potential to convert in-pit waste into additional resources within the 2026 MRE Whittle pit; or ii) out-of-pit expansion, consisting of mineralization located outside the 2026 MRE Whittle pit, which may potentially lead to the definition of new resources. Some of the reported intercepts may have contiguous shallower infill as well as deeper in-pit expansion (noted as “Both”). Maps showing hole locations are available at www.osiskometals.com.

Osisko Metals Chief Executive Officer Robert Wares commented: “Another series of excellent results from the north slope of Needle Mountain, including particularly two high-grade intercepts in holes 30-1236 and 30-1243, both located 500 to 600 metres west of the 2026 MRE model. The mineralized system continues to show grade improvement in the area around Needle Mountain and we are confident that these mineralized zones will be included in a westerly pit expansion in the next resource update.”

Highlights

• 211.5 metres averaging 0.59% Cu (out-of-pit expansion) in DDH 30-1243, including 28.5 metres averaging 2.31% Cu and 11.8 g/t Ag
• 86.5 metres averaging 1.36% (out-of-pit expansion) in DDH 30-1236, including 18.0 metres averaging 4.53% Cu and 23.3 g/t Ag
• 63.8 metres averaging 0.98% Cu (out-of-pit expansion) in DDH 30-1239, including 16.1 metres averaging 2.54% Cu and 8.98 g/t Ag
• 81.2 metres averaging 0.50% Cu (in-pit expansion) in DDH 30-1237, including 5.0 metres averaging 2.29% Cu and 16.4 g/t Ag
• 201.0 metres averaging 0.33%Cu (infill) in DDH 30-1245
• 54.0 metres averaging 0.44%Cu (in-pit expansion) in DDH 30-1241
  
  

Table 1: Infill and Expansion Drilling Results

* See explanatory notes below on copper equivalent values and Quality Assurance/Quality Controls.
** Infill refers to intercepts within the current MRE model; Expansion 1 refers to in-pit intercepts outside of the current MRE model; Expansion 2 refers to out-of-pit intercepts outside of the current MRE model. “Both” indicates drill holes that havecontiguous shallower infill as well as deeper in-pit expansion intercepts.

Additional comments

Drill holes 30-1236, 30-1239 and 30-1243, all located on the north slope of Needle Mountain, are expansion holes that threaded through pillars of the C Zone underground workings, intersecting significantly higher grades around and within the C Zone skarn horizon. Drill hole 30-1238 also targeted the C Zone horizon but failed to intersect the pillar and stopped in a stope.

Drill holes 30-1237, located near Copper Brook at the base of Needle Mountain, is also an expansion hole that threaded through a pillar of the C Zone underground workings, intersecting higher grades around and within the C Zone skarn horizon (81.2 metres averaging 0.50% Cu and 4.47 g/t Ag), and also at deeper levels (below the floor of the 2026 Whittle pit model) at the level of the E zone skarn horizon (46.3 metres averaging 0.58% Cu and 5.21 g/t Ag). Unusually high molybdenum grades (0.143% Mo) were also obtained in the latter horizon.

Drill hole 30-1244, located on the north slope of Needle Mountain, is an expansion hole that targeted the eastern margin of the C Zone underground workings, just outside the skarn alteration zone, returning significant intersections at two levels between the B Zone and C Zone horizons.

Drill hole 30-1242 is located near the southern margin of the Needle Mountain pit, approximately 730 m southwest of the limit of the 2026 MRE model, and tested an area where little mineralization was expected from historical drilling, yielding three significant mineralized intersections.

Drill holes 30-1240, 30-1241, 30-1245, 30-1246 and 30-1247, all located near Copper Brook at the southern portion of the 2026 MRE model, are infill holes with 30-1241 and 30-1247 being located in the margins of the 2026 MRE model. Grades and lengths of mineralized intersections are in line with the 2026 MRE block model.

Mineralization at Gaspé Copper is of porphyry copper/skarn type and occurs as disseminations and stockworks of chalcopyrite with pyrite or pyrrhotite and minor bornite and molybdenite. One prograde and at least five retrograde vein/stockwork mineralizing events have been recognized at Copper Mountain, which overprint earlier, stratiform, carbonate replacement skarn and porcellanite-hosted mineralization throughout the Gaspé Copper system. Porcellanite is a historical mining term used to describe bleached, pale green to white potassic-altered hornfels. Subvertical stockwork mineralization dominates at Copper Mountain whereas prograde bedding-parallel mineralization, which is mostly stratigraphically controlled, dominates in the area of lower Copper Mountain, Needle Mountain, Needle East, and Copper Brook. High molybdenum grades (up to 0.5% Mo) were locally obtained in both the C Zone and E Zone skarns away from Copper Mountain.

Table 2: Drill hole locations

*Extended hole 30-1037 – results are for total length of both holes
**Extended hole 30-1035 – results are for total length of both holes

The 2022 to 2024 Osisko Metals drill programs were focused on defining open-pit resources within the Copper Mountain stockwork mineralization (see May 6, 2024 MRE press release). Extending the resource model south of Copper Mountain into the poorly-drilled prograde skarn/porcellanite portion of the system subsequently led to a significantly increased resource, mostly in the Inferred category (see November 14, 2024 MRE press release), and additional drilling in 2025 led to an additional significant increase in resources, mostly in the Measured and Indicated categories (see April 14, 2026 MRE press release).

The current drill program is designed to convert the bulk of the remaining 2026 MRE Inferred resources to Measured and Indicated categories, as well as test the expansion of the overall resource laterally to the west, and to the south/southwest towards Needle East and Needle Mountain respectively.

Explanatory note regarding copper-equivalent grades

Copper Equivalent (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, payable metal factors, smelting and refining charges, transportation costs, and royalties. Hence the CuEq calculation is essentially based on net smelter return (NSR) values. NSR for each metal is estimated by applying metallurgical recoveries, payable factors, metal prices, and applicable smelting, refining, transportation, and penalty charges to the in-situ metal grades. CuEq grades are derived using a linear regression relationship established between copper grade and copper NSR, and then calculated by substituting total NSR (Cu + Mo + Ag) for copper NSR in the regression equation. The simplified formula is expressed as CuEq (%) = Cu (%) + 3.40327 × Mo (%) + 0.00008 × Ag (g/t)

Qualified Person

The scientific and technical content of this news release has been reviewed and approved by Mr. Bernard-Olivier Martel, P. Geo. (OGQ 492), an independent “qualified person” as defined by National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”).

Quality Assurance / Quality Control

Mineralized intervals reported herein are calculated using an average 0.12% CuEq lower cut-off over contiguous 20-metre intersections (shorter intervals as the case may be at the upper and lower limits of reported intervals). Intervals of 10 metres or less are generally not reported unless considered material.   True widths are estimated at 80 – 90 % of the reported core length intervals.

Osisko Metals adheres to a strict QA/QC program for core handling, sampling, sample transportation and analyses, including insertion of blanks and standards in the sample stream. Drill core is drilled in HQ or NQ diameter and securely transported to its core processing facility on site, where it is logged, cut and sampled. Samples selected for assay are sealed and shipped to ALS Canada Ltd.’s preparation facility in Sudbury. Sample preparation details (code PREP-31DH) are available on the ALS Canada website. Pulps are analyzed at theALSCanadaLtd.facilityinNorthVancouver,BC.Allsamplesareanalyzedbyfouraciddigestion followed by both ICP-AES and ICP-MS for Cu, Mo and Ag.

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. The Gaspé Copper mine site is located near Murdochville in Québec's Gaspé Peninsula. The Company is currently focused on resource expansion of the Gaspé Copper deposits, with current pit-constrained Measured and Indicated Mineral Resources of 1.83 Bt averaging 0.32% CuEq and Inferred Mineral Resources of 239 Mt averaging 0.46% CuEq (in compliance with NI 43-101).For more information, see Osisko Metals' April 14, 2026 news release entitled "Osisko Metals Announces Significant Increase in Mineral Resource at Gaspé Copper". 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 one of Canada's largest past-producing zinc mining camps, the Pine Point project, located in the Northwest Territories. The current mineral resource estimate for the Pine Point project consists of Indicated Mineral Resources of 49.5 Mt averaging 5.52% ZnEq and Inferred Mineral Resources of 8.3 Mt averaging 5.64% ZnEq (in compliance with NI 43-101). For more information, see Osisko Metals' June 25, 2024 news release entitled "Osisko Metals releases Pine Point mineral resource estimate: 49.5 million tonnes of indicated resources at 5.52% ZnEq". The Pine Point project is located on the south shore of Great Slave Lake, NWT, close to infrastructure, with paved road access, an electrical substation and 100 kilometres of viable haul roads.

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

Don Njegovan, President
Email: info@osiskometals.com
Phone: (416) 500-4129

Cautionary Statement on 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 tax treatment of the FT Units; the timing of incurring the Qualifying Expenditures and the renunciation of the Qualifying Expenditures; 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; the anticipated resource expansion of the Gaspé Copper system and Gaspé Copper hosting the largest undeveloped copper resource 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 geological modelling; insufficient data; equity and debt capital markets; future spot prices of copper and zinc; 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.

Photos accompanying this announcement are available at:
https://www.globenewswire.com/NewsRoom/AttachmentNg/35a75f62-b952-4938-bcbe-8b151cf19b88
https://www.globenewswire.com/NewsRoom/AttachmentNg/794a0884-2a24-4e36-be39-d71b9d9d52b7

20260928 Osisko Metals news release Figure 1/plan view

Gaspé Copper Drill Intercept Highlights September 28, 2026 (plan view).

20260928 Osisko Metals news release Figure 2/long section

Gaspé Copper Drill Intercept Highlights September 28, 2026 (long section).

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