Osisko Metals Incorporated (TSX: OM) (OTCQX: OMZNF) (FRANKFURT: 0B51) is pleased to announce additional new analytical results from the ongoing 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 38 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: “This new set of holes includes excellent results from infill drilling within the 2026 MRE model, particularly from holes 30-1251 and 30-1258. Hole 30-1251 intersected impressive high-grade mineralization in porcellanite above the historic E Zone underground workings, returning 94.4 metres averaging 1.47% Cu.”

Wares continued: “It has been our experience over the years that great deposits are full of great surprises. Hole 30-1258 appears to be just one of those types of surprises, having intersected 121 metres averaging 0.71% Cu hosted in a previously unknown porphyry intrusion below the E Zone skarn horizon at the south end of Copper Mountain. This new porphyry intrusion contains significant copper stockwork and veining, and it represents the first evidence of porphyry-hosted mineralization south of the main pit area. It may be indicative of a potential third, previously unknown (and untested) mineralized porphyry centre in the Gaspé Copper system, distinct from the two historically known porphyries in the main pit area and at the Porphyry Mountain DPEX target. Additional drilling will be designed to further test this interpretation.”

 Highlights

• 94.4 metres averaging 1.47% Cu (infill) in DDH 30-1251, includes 5.3 metres averaging 8.31% Cu and 51.0 g/t Ag and 185.5 metres averaging 0.41% Cu in a shallower interval
• 121.0 metres averaging 0.71% Cu (infill) in DDH 30-1258, includes 9.5 metres averaging 4.97% Cu and 56.3 g/t Ag
• 106.5 metres averaging 0.60% Cu (out-of-pit expansion) in DDH 30-1250, includes 15.9 metres averaging 1.92% Cu and 11.0 g/t Ag
• 218.8 metres averaging 0.35% Cu (infill) in DDH 30-1256
• 66.0 metres averaging 0.45% Cu (out-of-pit expansion) in DDH 30-1259
• 56.4 metres averaging 0.61% Cu (infill) in DDH 30-1255

Table 1: Infill and Expansion Drilling Results

7

0

5

31

* 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 have contiguous shallower infill as well as deeper in-pit expansion intercepts.

Additional comments

Drill holes 30-1248, 30-1249, 30-1253 and 30-1254, all located south and southwest of the Needle Mountain pit, tested areas where little mineralization was expected from historical drilling. All holes, with the exception of 30-1253, yielded multiple decametric mineralized intersections with grades ranging from 0.19% Cu to 0.50% Cu.

Drill hole 30-1250, located on the north slope of Needle Mountain, is an expansion hole that threaded through pillars of the C Zone underground workings, intersecting higher grades around and within the C Zone skarn horizon.

Drill hole 30-1259 is located on top of Needle Mountain East, approximately 320 metres south of the southern limit of the 2026 MRE model and near the southern extremity of the 2026 Whittle pit model. It is an expansion hole that intersected five decametric mineralized intervals with grades ranging from 0.12% Cu to 0.45% Cu. Mineralization was extended in this area to a vertical depth of 420 metres, indicating that the deposit is still open to the south, beyond the peak of Needle Mountain East.

Drill holes 30-1251, 30-1252, 30-1255, 30-1256, 30-1257 and 30-1258, all located near Copper Brook at the southern portion of the 2026 MRE model, are infill holes that intersected mineralization in line with the 2026 MRE block model, with the exception of higher-than-expected grades in 30-1251 and 30-1258, as discussed above.

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

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

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 the ALS Canada Ltd. facility in North Vancouver, BC. All samples are analyzed by four acid digestion 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.