Mr. Robert Wares reports

OSISKO METALS LAUNCHES DEEP PORPHYRY EXPLORATION PROJECT ("DPEX") AND CONFIRMS 852 METRES AVERAGING 0.95% CUEQ AT HISTORIC PORPHYRY MOUNTAIN DEPOSIT

Osisko Metals Inc. has released initial results from the start of the re-evaluation of the Gaspe copper project's (the GCP) Porphyry Mountain deposit, discovered in 1994 by mine-site exploration work conducted by Noranda Inc. Osisko's Deep Porphyry Exploration project (the DPEX), planned for 2026, will include a new deep drill program, reanalysis of historic drill core and remodelling of historic information designed to outline a National Instrument 43-101 inferred mineral resource estimate (MRE) on the Porphyry Mountain Cu-Mo (copper-molybdenum) deposit by year-end.

The DPEX program will be conducted separately from the current resource evaluation work at GCP, to provide preliminary information as to the potential of this deposit.

Today's news release includes reassaying of core from one historical drill hole (DDH 30-0943) drilled in 2011 by Xstrata in the Porphyry Mountain deposit which is located at depth from the current GCP NI 43-101 MRE (see Nov. 14, 2024, news release), approximately 1,100 metres laterally northeast from the centre of the Copper Mountain pit.

Reassayed historical core from DDH 30-0943 returned 852.0 metres averaging 0.70 per cent Cu, 2.92 g/t Ag (silver) and 0.062 per cent Mo (0.95 per cent CuEq (copper equivalent)) from 998.0 to 1850.0 metres, which confirms previously obtained historical results (see Table 1). Many of the historical holes drilled by previous operators that reached the lower portion of the Porphyry Mountain deposit were stopped in mineralization (see Table 1), demonstrating that the deposit remains open at depth.

Osisko Metals chief executive officer Robert Wares commented: "These very promising results launch our 2026 DPEX resource evaluation program at Porphyry Mountain. Following the anticipated Q1 2026 release of our MRE update on the GCP Copper Mountain deposit, and in addition to the currently planned 2026 expansion drilling on the GCP Needle Mountain and Needle East zones, the DPEX resource evaluation program on Porphyry Mountain will include deep drilling on the deposit and thorough reassaying of available historical drill core. This should establish its true depth and reveal the full potential of the deposit, with the objective of releasing a maiden inferred MRE on Porphyry Mountain by the end of 2026. We anticipate that the updated GCP Copper Mountain open pit will reach significant depths near the end of its mine life, and this would potentially allow for future ramp access to the deeper, higher-grade DPEX Porphyry Mountain deposit."

About Porphyry Mountain

The Porphyry Mountain deposit was discovered by Noranda in 1994. It is located approximately 1,100 metres northeast of the centre of the GCP Copper Mountain pit. The upper limit of the Porphyry Mountain deposit occurs at depths of approximately 1,000 to 1,200 metres. The porphyry-style stockwork of Cu-Mo veins, hosted by a separate porphyry intrusion at its core (relative to Copper Mountain), forms a subvertical deposit, roughly cylindrical in shape and measuring about 500 metres in diameter, having been defined by historical drilling over a minimum vertical length of 680 metres. Most of the historical holes stopped in mineralization at depths between 1,700 to 2,100 metres, indicating that the deposit remains open at depth. Both copper and molybdenum average grades are higher compared with the GCP Copper Mountain deposit. All analytical pulps from the historical drill hole (DDH 30-0943) reassaying program that graded greater than 1 per cent Cu are also currently being analyzed for gold.

Explanatory note regarding copper-equivalent grades

Copper equivalent grades are expressed for purposes of simplicity and are calculated taking into account: 1) metal grades; 2) estimated long-term prices of metals: $4.25 (U.S.)/pound copper, $20.00/lb molybdenum and $24 (U.S.)/oz silver; 3) estimated recoveries of 92 per cent, 70 per cent and 70 per cent for Cu, Mo and Ag, respectively; and 4) net smelter return value of metals as percentage of the price, estimated at 86.5 per cent, 90.7 per cent and 75.0 per cent for Cu, Mo and Ag, respectively.

Qualified person

The scientific and technical content of this news release has been reviewed and approved by Jeff Hussey, PGeo (OGQ 821), a qualified person as defined by National Instrument 43-101 -- Standards of Disclosure for Mineral Projects.

Quality assurance/quality control

The mineralized interval reported herein was calculated using an average 0.30 per cent 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).

True extent is estimated at 100 per cent 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 the ALS Canada Ltd. facility in North Vancouver, B.C. All samples are analyzed by four-acid digestion followed by both ICP-AES and ICP-MS for Cu, Mo and Ag.

About Osisko Metals Inc.

Osisko Metals 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-per-cent interest in the past-producing Gaspe copper mine from Glencore Canada Corp. in July, 2023. The Gaspe copper mine is located near Murdochville in Quebec's Gaspe Peninsula. The company is currently focused on resource expansion of the Gaspe copper system, with current indicated mineral resources of 824 million tonnes averaging 0.34 per cent CuEq and inferred mineral resources of 670 Mt averaging 0.38 per cent CuEq (in compliance with NI 43-101). For more information, see Osisko Metals' Nov. 14, 2024, news release entitled "Osisko Metals Announces Significant Increase in Mineral Resource at Gaspe Copper." Gaspe copper hosts the largest undeveloped copper resource in eastern North America, strategically located near existing infrastructure in the mining-friendly province of Quebec.

In addition to the Gaspe copper project, the company is working with Appian Capital Advisory LLP through the Pine Point Mining Ltd. 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 per cent ZnEq and inferred mineral resources of 8.3 Mt averaging 5.64 per cent 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 per cent 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.

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