Osisko's High-Grade Drill Results De-Risk Cariboo's Path to Production

MONTREAL, QC – June 09, 2026 – Osisko Development Corp. today announced the completion of a major drilling program at its flagship Cariboo Gold Project in British Columbia, revealing high-grade gold intercepts that significantly bolster the company's confidence as it marches toward production. The results, highlighted by impressive finds such as 44.68 grams per tonne (g/t) gold over 1.5 meters, are a critical step in a much larger strategic play: methodically de-risking one of Canada’s next major gold mines before the first ounce is poured.

While the eye-popping numbers—including one interval of 133.62 g/t gold over half a meter—grab headlines, the real story lies in the disciplined execution of the company's strategy. This wasn't a wildcat exploration program seeking a discovery; it was a systematic, high-density infill drilling campaign designed to transform a well-defined resource into a predictable, mineable reserve. For a company on the cusp of transitioning from developer to producer, this kind of data-driven validation is paramount.

From Drilling Data to Bankable Reserves

The recently completed program involved over 13,600 meters of infill drilling on a tight 10-meter spacing within the Lowhee Zone, one of the satellite deposits at the expansive Cariboo project. Infill drilling is the meticulous, often unglamorous work of confirming what geologists believe is already there. By drilling between known points of mineralization, companies can increase the certainty of their geological model, upgrade resources from inferred to indicated or measured categories, and ultimately convert them into bankable reserves that underpin a mine's economics.

Chris Lodder, President of Osisko Development, highlighted the strategic value of this precision. "The completion of the tighter infill drill spacing gives us a better understanding of vein corridor spatial geometries and local variability," he stated in the release. This improved understanding is crucial for refining production designs and sequencing, ensuring that mining operations can be planned with maximum efficiency and minimal surprises.

The data from these 142 new drill holes, along with nearly 3,000 meters of additional exploration drilling, will now feed into an updated localized block model. This digital 3D map of the orebody is the foundational tool for mine planners. The company anticipates the final updated model in the second quarter of 2026, which could support the addition of new planned mining areas, known as stopes, potentially enhancing the project's overall value and mine life.

Fortifying a "Shovel-Ready" Asset

These technical advancements are happening at a project that already boasts a formidable profile. The Cariboo Gold Project is a rarity in the global mining industry: a large-scale, high-grade gold project in a top-tier jurisdiction that is fully permitted and "shovel-ready." After successfully navigating British Columbia's rigorous environmental assessment process, Osisko secured its key Mines Act and Environmental Management Act permits in late 2024, clearing the final regulatory hurdles for construction.

The project’s 2025 Feasibility Study outlines a robust economic case, projecting average annual production of 190,000 ounces of gold over a 10-year mine life, with an impressive after-tax net present value of C$943 million at a US$2,400/oz gold price. With probable mineral reserves already standing at over 2 million ounces of gold, the project is on solid footing. The current drilling at the Lowhee Zone, which represents about 5% of the total reserve, demonstrates a commitment to optimizing every component of this large mineral system.

With construction slated to begin in the third quarter of 2025 and first gold production targeted for the second half of 2027, every piece of new data helps solidify the timeline. By refining the geological model now, Osisko is ensuring that the C$881 million in initial capital required to build the mine is deployed with the highest degree of confidence.

The Strategy Behind the Capital

The successful drilling program doesn't exist in a vacuum; it is intrinsically linked to Osisko Development's astute financial strategy. In the past year, the company has methodically built a war chest to fund Cariboo's construction, securing a US$450 million project loan facility and raising over US$200 million in a private placement. Most recently, the company closed a US$300 million convertible senior notes offering, a financing instrument that signals strong market belief in the company’s long-term equity value.

This access to capital is a direct reflection of investor confidence, which is built on tangible progress and de-risking milestones like the successful infill program. The high-grade results provide tangible proof that the asset's quality matches the projections, justifying the significant investment required to bring it to life. This synergy between operational execution and financial stewardship is a hallmark of the Osisko group of companies, known for creating the Canadian Malartic mine, one of the country's largest gold producers.

Further signaling its strategic evolution, the company has proposed a name change to "Osisko Gold Group Inc." According to company sources, the move is intended to better reflect its identity as it advances its portfolio of North American gold assets, with the now de-risked Cariboo project leading the charge.

A Modern Gold Rush in British Columbia

The Cariboo Gold Project is a modern revival of one of Canada's most storied mining districts, the Wells-Barkerville camp, which first saw a gold rush in the 1860s. Today, Osisko's work is part of a renewed interest in British Columbia's vast mineral wealth, which includes an estimated 130 million ounces of in-ground gold resources. The company's ability to successfully permit a major new mine demonstrates that responsible resource development can thrive within the province's robust regulatory and environmental framework.

As Osisko Development moves toward a final construction decision, the latest drilling results serve as a powerful confirmation of its methodical approach. In an industry where geological uncertainty is a primary risk, the company is systematically replacing assumptions with hard data, building a foundation of certainty that is essential for constructing and operating a successful, long-life mine.