More than 13,000m of drilling and 33 holes completed since the start of summer 2026 drilling

Sirios Resources Inc. (TSX-V: SOI) (OTCQB: SIREF) (FSE: 377A) announces the assay results of the first 5 holes totaling 1,753 m of Phase 1 drilling at its Cheechoo gold project, located in the Eeyou Istchee Baie-James region of Quebec, Canada.

Highlights from these first results include:

• 2.40 g/t Au over 48.5 m, including 77.65 g/t Au over 1.1 m (CH26-326)
• 1.49 g/t Au over 37.6 m (CH26-326)
• 1.16 g/t Au over 32.2 m, including 12.88 g/t Au over 1.5 m (CH26-327)
• 2.28 g/t Au over 10.3 m, including 10.39 g/t Au over 1.5 m (CH26-327)
• 0.77 g/t Au over 10.3 m (CH26-300E)

Visible Gold in 8 Drill Holes

Visible gold has been observed in several locations in 8 drill holes, including drill hole CH26-326, and 7 others for which assay results are pending. To date, 33 holes have been completed and four more are in progress for a total drilled length of 13,555 meters, including the extension of hole #300 (CH26-300E). Four drill rigs remain in operation at Cheechoo.

“We are pleased with the initial results of our 2026 summer drilling program,” said Dominique Doucet, Head of Exploration for Sirios. “From the very first holes, good results were obtained both outside and within the conceptual pit of our resources, confirming the potential for expansion of the deposit in the tonalite as well as the depth extension of the metasedimentary zone to the east.”

“These preliminary results, which represent less than 10% of the planned drill holes, support our thesis that the resource at Cheechoo has the potential to become more significant than indicated in the 2025 resource estimate,” said Jean-Félix Lepage, CEO of Sirios. “With four active drill rigs, we anticipate completing Phase 1 in September and launching the updated resource estimate thereafter.”

Figure 1: Locations of observed visible gold

2026 DRILL PROGRAM: ASSAY RESULTS FROM FIRST DRILL HOLE

Figure 2: Location of drill holes CH26-326 to CH26-329, and extension of CH26-300E

Furthermore, the onsite analysis campaign involved scanning 24,299 m of core, including drill holes from the current campaign, using Élémission’s ECORE Laser-Induced Breakdown Spectroscopy (LIBS) instrument. The analysis campaign will continue until mid-September.

Quality Assurance and Quality Control

The drill cores were described and sampled by Sirios personnel at the Cheechoo Exploration Camp. The cores were split into two halves, one of which was sent to a certified commercial laboratory for analysis, and the other was retained for future reference. Following a strict analytical quality assurance and quality control program, blanks and certified reference materials were incorporated into the sampling sequence. Samples were analyzed for gold, on approximately 500 g of crushed material, using the Photon Assay™ method by the MSALABS laboratory located in Val-d’Or. Samples containing visible gold were analyzed using the entire crushed sample with the Photon Assay™ method.

Qualified Person

The scientific and technical content of this press release has been reviewed and approved by Dominique Doucet, P.Eng., Head of Exploration at Sirios, a Qualified Person as defined by Canadian National Instrument 43-101.

Additional information on previously announced marketing agreement

On April 1st, 2026, the Company announced that it has entered into a marketing services agreement with Resources Stock Digest (“RSD”). RSD did not receive common shares or options as remuneration, but the owners of RSD are shareholders of the Company.

About the Cheechoo Project

Cheechoo is located approximately 15 km from the Éléonore mine and near infrastructure, including roads and hydroelectric facilities, in the Eeyou Istchee Baie-James region of Canada. Cheechoo is in the resource development stage, with 35 Mt of indicated resources at 1.12 g/t (1,262 koz) and 42.7 Mt of inferred resources at 1.23 g/t (1,688 koz) (see NI 43-101 Technical Report on the Cheechoo Project with an Updated Mineral Resource Estimate for the Cheechoo Gold Deposit, Eeyou Istchee James Bay, Québec, dated August 22, 2025 and deposited on the Company’s website and on SEDAR+). In addition, a conceptual exploration target of 31 to 40 million tonnes of mineralization grading between 1.27 and 1.45 g/t Au has been estimated.

About Sirios

Sirios Resources is a Quebec-based mineral exploration company focused on developing its Cheechoo gold deposit, as well as exploring and advancing its other high-potential gold projects in the Eeyou Istchee James Bay region of Canada. On December 11, 2025, Sirios announced the details of the acquisition of OVI Mining, a milestone in the company’s history.