Denison Closes Transaction with Skyharbour, Forms Four Joint Ventures Near Wheeler River

• Transaction with Skyharbour Resources closed, forming four joint ventures from claims previously comprising the Russell Lake uranium project
• Denison operates Wheeler North (49% interest) and Wheeler River Inliers (70% interest) joint ventures
• Skyharbour operates Russell Lake and Getty East joint ventures, where Denison holds 20% and 30% interests respectively
• Earn-in option agreements allow Denison to increase ownership in Wheeler North and Getty East to 70%
• Properties are located directly adjacent to Denison's Wheeler River project in Saskatchewan's Athabasca Basin

Denison Mines Corp. (TSX: DML; NYSE American: DNN) is a Canadian uranium exploration and development company with focus on Saskatchewan's Athabasca Basin. The company holds a 95% interest in the Wheeler River uranium project, described as the largest undeveloped uranium project in the eastern Athabasca Basin. Denison's Saskatchewan interests include a 22.5% stake in the McClean Lake Joint Venture, which includes the McClean Lake uranium mill and unmined deposits, a 25.17% interest in the Midwest Joint Venture, and a 70.55% interest in deposits on the Waterbury Lake property. The company's direct ownership covers approximately 457,000 hectares in the Athabasca Basin region.

Transaction Details and Joint Venture Structure

Denison has closed the previously announced transaction with Skyharbour Resources to acquire properties adjacent to Wheeler River. The transaction creates four separate joint ventures covering ground that formerly comprised Skyharbour's Russell Lake uranium project. The structure divides operational responsibilities between the two companies.

Under the arrangement, Denison serves as operator for two joint ventures. The company holds a 49% ownership interest in Wheeler North and a 70% interest in Wheeler River Inliers. Skyharbour operates the Russell Lake and Getty East joint ventures, where Denison's ownership interests are 20% and 30% respectively.

The companies have also executed earn-in option agreements. These agreements provide Denison the option to increase its ownership in the Wheeler North and Getty East joint ventures to 70%. The joint ventures are intended to facilitate collaboration between the companies' technical teams and accelerate evaluation of exploration ground near Wheeler River.

Ownership Stakes and Option Provisions

The four joint ventures feature different ownership splits. In Wheeler North, Denison holds 49% while operating the property. The Wheeler River Inliers joint venture gives Denison both operational control and a 70% ownership position. For the two Skyharbour-operated ventures, Denison maintains 20% in Russell Lake and 30% in Getty East.

The earn-in option agreements cover two of the four properties. Denison can exercise options to increase its stake in Wheeler North and Getty East from current levels to 70%. The terms of these earn-in agreements were not disclosed in the release.

This structure allows Denison to participate in exploration across multiple properties while distributing operational responsibilities. Skyharbour retains majority interests in two ventures and operational control, while Denison holds majority or significant minority positions across all four properties.

Property Location and Wheeler River Context

The joint venture properties are positioned directly adjacent to Denison's Wheeler River project. Wheeler River is located in the eastern Athabasca Basin of northern Saskatchewan, described in company materials as the largest undeveloped uranium project in the infrastructure-rich eastern portion of the basin.

Wheeler River includes two deposits. The Phoenix deposit completed a feasibility study in 2023 for in-situ recovery (ISR) mining. The Gryphon deposit was evaluated in an updated 2018 pre-feasibility study for conventional underground mining. According to Denison, both deposits have the potential to be competitive with low-cost uranium operations globally, based on their respective studies.

Permitting for the Phoenix ISR operation began in 2019. The project received provincial environmental assessment approval from Saskatchewan in July 2025. The Canadian Nuclear Safety Commission concluded public hearings in December 2025 for federal environmental assessment approval and the project construction licence. The Russell Lake properties now under joint venture sit adjacent to this development.

Next Steps

The joint ventures are now operational following the transaction close. Denison and Skyharbour will proceed with exploration activities on the properties adjacent to Wheeler River. The companies stated the arrangement is designed to accelerate evaluation of the ground surrounding Denison's flagship project.

For Wheeler River itself, Denison awaits federal approval decisions following the December 2025 Canadian Nuclear Safety Commission hearings. The company is progressing through final permitting requirements for the Phoenix ISR operation while the new joint ventures provide exploration opportunities on adjacent ground.

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