Mr. David Cates of Denison reports

DENISON TO FILE EARLY WARNING REPORT IN RESPECT OF FOREMOST CLEAN ENERGY LTD.

Denison Mines Corp. has made a further investment in Foremost Clean Energy Ltd. pursuant to its rights under its investor rights agreement with Foremost.

Foremost had completed certain prior share issuances, and Denison has acquired an additional 485,000 common shares at a price of $2.20 per common share, for aggregate subscription price of $1,067,000.

Denison held 1,977,410 Foremost common shares, representing approximately 16 per cent of Foremost's issued and outstanding shares prior to closing of the issuance to Denison. On completion of the issuance to Denison, Denison holds 2,462,410 Foremost common shares, representing approximately 19 per cent of Foremost's then issued and outstanding shares. Denison also holds 607,600 Foremost warrants, representing approximately 17 per cent of the issued and outstanding warrants of Foremost. Denison will be filing an early warning report pursuant to National Instrument 62-103 in respect of the change in its common share holdings in Foremost.

Additional information

The Foremost shares were acquired by Denison for investment purposes. The company intends to review, on a continuous basis, various factors related to its investment in Foremost, and may decide to acquire or dispose of additional securities of Foremost as future circumstances may dictate, including under its pre-emptive rights under the investor rights agreement.

Further information will be available in the early warning report to be filed under Foremost's profile on SEDAR+.

About Denison Mines Corp.

Denison is a uranium mining, exploration and development company with interests focused in the Athabasca basin region of Northern Saskatchewan, Canada. The company has an effective 95-per-cent interest in its flagship Wheeler River uranium project, which is the largest undeveloped uranium project in the infrastructure-rich eastern portion of the Athabasca basin region of Northern Saskatchewan. In mid-2023, a feasibility study was completed for the Phoenix deposit as an in situ recovery mining operation, and an update to the previously prepared 2018 prefeasibility study was completed for Wheeler River's Gryphon deposit as a conventional underground mining operation. Based on the respective studies, both deposits have the potential to be competitive with the lowest-cost uranium mining operations in the world.

Permitting efforts for the planned Phoenix ISR operation commenced in 2019 and are nearing completion with approval of the project's environmental assessment received from the Province of Saskatchewan and Canadian Nuclear Safety Commission hearing dates set in the fall of 2025 for federal approval of the EA and project construction licence.

Denison's interests in Saskatchewan also include a 22.5-per-cent ownership interest in the McClean Lake joint venture, which includes unmined uranium deposits (with the mining at the McClean North deposit through the MLJV's surface access borehole resource extraction mining method having commenced in July, 2025) and the McClean Lake uranium mill (currently utilizing a portion of its licensed capacity to process the ore from the Cigar Lake mine under a toll milling agreement), plus a 25.17-per-cent interest in the Midwest joint venture's Midwest Main and Midwest A deposits, and a 70.55-per-cent interest in the Tthe Heldeth Tue and Huskie deposits on the Waterbury Lake property. The Midwest Main, Midwest A, THT and Huskie deposits are located within 20 kilometres of the McClean Lake mill. Taken together, Denison has direct ownership interests in properties covering approximately 384,000 hectares in the Athabasca basin region.

Additionally, through its 50-per-cent ownership of JCU (Canada) Exploration Company Ltd., Denison holds additional interests in various uranium project joint ventures in Canada, including the Millennium project (JCU, 30.099 per cent), the Kiggavik project (JCU, 33.8118 per cent) and Christie Lake (JCU, 34.4508 per cent).

In 2024, Denison celebrated its 70th year in uranium mining, exploration and development, which began in 1954 with Denison's first acquisition of mining claims in the Elliot Lake region of Northern Ontario.

About Foremost Clean Energy Ltd.

Foremost Clean Energy is an emerging North American uranium and lithium exploration company with an option to earn an up-to-70-per-cent interest in 10 prospective uranium properties spanning over 330,000 acres in the prolific, uranium-rich Athabasca basin. As the demand for carbon-free energy continues to accelerate, domestically mined uranium and lithium are poised for dynamic growth, playing an important role in the clean energy mix of the future. Foremost's uranium projects are at different stages of exploration, from grassroots to those with significant historical exploration and drill-ready targets. Its mission is to create significant discoveries, alongside and in collaboration with Denison, through systematic and disciplined exploration programs.

We seek Safe Harbor.