NexGen Energy

The inputs used in the pricing model as at June 30, 2026 and December 31, 2025 are as follows: June 30, 2026 December 31, 2025 Volatility 45.00% 43.00% Expected life 2.9 years 3.4 years Risk free interest rate 3.95% 3.35% Expected dividend yield 0% 0% Credit spread 17.55% 15.64% Underlying share price of the Company US$9.39 US$9.20 Conversion exercise price US$10.73 US$10.73 Exchange rate (C$:US$) $ 0.7048 $ 0.7287 10.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

These condensed interim consolidated financial statements follow the same accounting policies and methods of application as the Annual Financial Statements except for assets under construction and borrowing costs (Note 3b)).

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

Notes to the Condensed Interim Consolidated Financial Statements For the three and six months ended June 30, 2026 (expressed in thousands of Canadian dollars, except as otherwise stated) - Unaudited b) Adoption of material accounting policies Assets under Construction Assets under construction include the costs of the construction of mining and processing facilities, along with borrowing costs capitalized during construction, on a mineral property for which technical feasibility and commercial viability have been demonstrated, after the relevant exploration and evaluation asset has been tested for impairment.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

Borrowing Costs Borrowing costs attributable to the construction of qualifying assets, which take a substantial period of time to make ready for their intended use, are added to the cost of the assets until such time as the assets are substantially complete and ready for their intended use.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

The amount of borrowing costs capitalized cannot exceed the actual amount of borrowing costs incurred in a period.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

All other borrowing costs are expensed in the period in which they are incurred.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

STRATEGIC INVENTORY On May 28, 2024, the Company closed an agreement to purchase 2,702,411 pounds of natural uranium concentrate ("U 3 O 8 ") for an aggregate purchase price of $341,150 (US$250 million), which was satisfied through the issuance of US$250 million aggregate principal amount of five year, 9.0% per annum (6% payable in cash, 3% payable in common shares of the Company) unsecured convertible debentures (the "2024 Debentures") (Note 9).

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

The strategic inventory is valued at the lower of cost and net realizable value of $341,150 as at June 30, 2026.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

While the Company's strategic inventory is not a financial instrument, the prices of uranium are quoted in US dollars and routinely traded in US dollars, and fluctuations in the Canadian dollar relative to the US dollar can significantly impact the valuation of the Company's physical uranium in Canadian dollars.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

Management s Discussion and Analysis for the three and six months ended June 30, 2026 (expressed in thousands of Canadian dollars, except as noted) BUSINESS OVERVIEW NexGen is a British Columbia corporation with a focus on developing into production the 100% owned Rook I Project (the "Rook I Project" or the "Project") located in the southwestern Athabasca Basin of Saskatchewan, Canada.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

The Program includes the establishment of a temporary exploration airstrip, expansion of the exploration accommodation camp facilities by 373 beds (to approximately 600 beds), and site access road improvements.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

NexGen is an exploration and development company and is subject to risks and challenges similar to companies at a comparable stage.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

These risks include, but are not limited to, development and operational risks inherent in development stage mining projects; uncertainties in the exploration for mineral resources; changes in government policies and regulations; the ability to obtain the necessary environmental permits or, alternatively, NexGen's ability to dispose of its exploration and evaluation assets on an advantageous basis; global economic and uranium price volatility; and the challenges of securing adequate capital, all of which are uncertain.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

Accordingly, significant movements in share price may affect the valuation of the convertible debentures which may adversely impact the Company's earnings.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

Please see the section, " Cautionary Note Regarding Forward-Looking Information and Statements " for a discussion of the risks, uncertainties, and assumptions used to develop the Company's forward-looking information.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

Management s Discussion and Analysis for the three and six months ended June 30, 2026 (expressed in thousands of Canadian dollars, except as noted) Key Sources of Estimation Uncertainty The preparation of consolidated financial statements in conformity with IFRS Accounting Standards requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and related notes to the consolidated financial statements.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026

The significant assumptions about the future and other major sources of estimation uncertainty as at the end of the reporting period that have a significant risk of resulting in a material adjustment to the carrying amounts of the Company's assets and liabilities include mineral property, plant and equipment, exploration and evaluation assets, strategic inventory, convertible debentures, and share-based payments.

SEC original ↗NexGen Energy — Earnings release (6-K exhibit)EX-99Aug 5, 2026