Name of the Project
Cariboo gold project.

Location
British Columbia, Canada.

Project Owner/s
North American gold development company Osisko Gold Group Inc, formerly Osisko Development Corp. The name change took effect on July 14, 2026.

Project Description
The project is envisioned as a traditional underground operation using mechanised longhole open stoping to extract ore from gold-bearing vein corridors – a complicated network of mineralised quartz veins predominantly hosted within unmineralised sandstone.

Underground mining will target five mineralised zones along 4 400 m of strike, accessed by two ramps – the currently operational Cow portal and the new Valley portal.

Each zone includes several vein systems extending to a vertical depth of about 650 m.

The April 2025 optimised feasibility study estimates average production of about 190 000 oz/y of gold over a ten-year mine life, and average production of 202 000 oz/y over the first five years. Peak throughput is estimated at 4 900 t/d.

The feasibility study proposes ore beneficiation to be exclusively completed at the mine site complex.

This would produce saleable gold doré from a gravity concentrate and about 66 t/d of high-grade flotation concentrate averaging about 133 g/t gold.

Significant opportunities exist to potentially enhance project economics and extend the life-of-mine through conversion of mineral resources adjacent to mineral reserves through infill drilling.

Potential Job Creation
The optimised feasibility study shows strong support for local employment, with up to 613 direct jobs expected to be created during peak construction and 525 permanent jobs during operations.

The construction and exploration workforce exceeded 400 active personnel in October.

Net Present Value/Internal Rate of Return
The August 2026 financial update, announced in September, estimates an after-tax net present value, at a 5% discount rate, of C$2.323-billion and an internal rate of return of 34.7%, with a 2.2-year payback from commercial production, using a long-term consensus gold price of $3 570/oz and C$1.38/$1. These results use the revised remaining-capital basis.

Capital Expenditure
At September 30, 2026, cumulative costs incurred were about C$355-million, including indirect and owner’s costs. The estimated remaining construction cost is estimated at C$907-million, net of incurred costs, leases and estimated preproduction revenue.

Planned Start/End Date
The final investment decision was announced on September 14, 2026. First gold pour is targeted for the first quarter of 2029 and commercial production for the second half of 2029.

Latest Developments
Osisko has reported that the project is about 28% complete on a cost-incurred basis at September 30. Detailed engineering was about 42% complete; more than half of the procurement packages have been awarded, with about C$360-million committed.

Underground development reached about 3.4 km. Valley portal earthworks were 85% complete, with access and ventilation portals expected in the fourth quarter of 2026. The year-end development-rate target fell from 500 m a month to 360 m a month, owing to excavation conditions, noise-control methods and concrete-curing requirements.

Key Contracts, Suppliers and Consultants
BBA Engineering (optimised feasibility study); JDS Energy & Mining (project and construction management; continuing underground development and related works); Caterpillar (loaders and haul trucks); MacLean Engineering (support and service vehicles); and Epiroc (drill rigs and jumbos).

Contact Details for Project Information
Osisko Gold Group Inc, tel +1 514 940 0685; email info@osiskogold.ca or ir@osiskogold.ca.