Mr. David Cates reports

DENISON ANNOUNCES CLOSING OF US$345 MILLION CONVERTIBLE SENIOR NOTES OFFERING

Denison Mines Corp. has closed its previously announced offering of convertible senior unsecured notes due 2031 for an aggregate principal amount of $345-million (U.S.), which includes the upsized offering of $300-million (U.S.) and the exercise in full of the $45-million option granted to the initial purchasers of the notes.

Denison's president and chief executive officer, David Cates, commented: "Denison is humbled by the overwhelming support we received from the convertible note investment community for this offering of a 'U.S.-style' convertible note with a cash-settled capped call overlay -- a novel transaction for a Canadian-domiciled and Toronto Stock Exchange-listed company. Any conversions of the notes, prior to the maturity date of Sept. 15, 2031, may be settled in cash, Denison common shares or a combination of both, at Denison's election.

"With an annual coupon rate of 4.25 per cent, the notes are estimated to save Denison over $100-million (U.S.) in interest payments over the life of the instrument when compared to the range of expected interest payments associated with traditional project debt financing alternatives. Additionally, the purchase by Denison of the capped calls helps protect the company against increases in the conversion settlement value of the notes, and the potential equity dilution associated therewith, by significantly raising the effective conversion price for the notes from the $2.92 (U.S.)/share initial conversion price of the notes up to the $4.32 (U.S.)/share cap price of the capped calls.

"Over all, the proceeds of the offering put Denison in an excellent financial position to make a future final investment decision (FID) and to commence construction, following the anticipated receipt of upcoming regulatory approvals, for the company's flagship Phoenix in-situ recovery (ISR) uranium mine in Northern Saskatchewan."

Summary of the offering

• Approximately $333-million (U.S.) of net proceeds after deducting the initial purchasers' commissions and other fees and expenses. Cantor Fitzgerald & Co. and Scotia Capital (USA) Inc. acted as active bookrunners.
• Cash interest coupon of 4.25 per cent per annum, payable semi-annually in arrears on March 15 and Sept. 15 of each year, beginning March 15, 2026.
• The initial conversion rate for the notes is 342.9355 common shares of Denison per $1,000 (U.S.) principal amount of notes, equivalent to an initial conversion price of approximately $2.92 (U.S.) per share (approximately 35 per cent premium to the closing price of the shares at the time of pricing on Aug. 12, 2025).
• The effective conversion price of the notes is increased up to $4.32 (U.S.) per share (approximately 100-per-cent premium to the closing price of the shares at the time of pricing on Aug. 12, 2025) after giving effect to the capped call overlay option strategy, whereby Denison purchased cash-settled call options with a strike price equal to initial conversion price of the notes ($2.92 (U.S.)) and with a cap price of $4.32 (U.S.). The purchase price for the capped call transactions was approximately $35.36-million (U.S.).
• Conversions of the notes may be settled in shares, cash, or a combination of shares and cash, at Denison's election. Additionally, Denison will have the right to redeem the notes in certain circumstances and will be required to repurchase the notes upon the occurrence of certain events.
• The notes may only be converted by holders prior to June 15, 2031, in certain circumstances, and may be converted by holders after June 15, 2031.
• The notes will mature on Sept. 15, 2031. Any notes not converted, repurchased or redeemed prior to the maturity date will have their principal amount repaid by Denison in cash at maturity.
• The company intends to use the net proceeds from the offering for expenditures to support the evaluation and development of the company's uranium development projects, including the Wheeler River uranium project and general corporate purposes.

Further information concerning the notes and the capped call transactions, including illustrative settlement scenarios, may be found on the investors -- presentations page of the company's website. The indenture for the notes and form of confirmation for the capped call transactions have been or will be filed by the company under its profile on SEDAR+ and on EDGAR, and it is recommended they be read in their entirety for a fulsome understanding of the notes and capped call transactions.

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 ISR 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 (EA) 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 (MLJV), which includes unmined uranium deposits (with the mining at the McClean North deposit via the MLJV's surface access borehole resource extraction (SABRE) 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 (THT) 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.

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