Forward-Looking Information and Technical Disclosure

Information Contained on this Website

This website and the information and materials contained on or made available through it provide a summary description of NexGen Energy Ltd. (“NexGen” or the “Company”) and its business and do not purport to be complete. The information is not, and in no circumstances is to be construed as, a prospectus, advertisement or public offering of securities. No securities regulatory authority or similar authority has reviewed or in any way passed upon the information on this website or the merits of the Company’s securities, and any representation to the contrary is an offence.

Except where otherwise indicated, the information has been prepared by NexGen. Information attributed to third-party sources reflects the information provided by those sources, and NexGen does not make any representation or warranty as to its accuracy or completeness.

Documents, news releases, presentations, reports, articles, videos and other dated materials made available on or through this website speak only as of their respective dates. The posting of such materials on this website does not imply that the information contained in them is accurate or complete as of any subsequent date, and NexGen undertakes no obligation to update such materials except as required by applicable securities laws.

Forward-Looking Information

This website contains “forward-looking statements” within the meaning of applicable United States securities laws and regulations and “forward-looking information” within the meaning of applicable Canadian securities legislation (collectively, “forward-looking information”). Forward-looking information on this website includes, but is not limited to, statements and information with respect to mineral reserve and mineral resource estimates for the Arrow Deposit; the Rook I Project; the Patterson Corridor East discovery; estimates of NexGen’s uranium production, grade, recoveries, throughput and mine life; planned mining methods, processing, automation, infrastructure and the Underground Tailings Management Facility; capital costs, operating costs, sensitivities and expected project economics; uranium prices, price assumptions, contracting strategies, future sales, market-related pricing and anticipated returns from uranium production; foreign exchange and other economic assumptions; construction activities, construction progress, engineering, procurement, shaft sinking, mine development, commissioning, ramp-up and operations, including the timing, cost and successful completion of those activities; planned work programs, exploration activities, development activities and budgets; the anticipated results, significance and potential implications of exploration activities and completed drill results, including at Patterson Corridor East; the potential identification or expansion of mineralization and future mineral resources; governmental, regulatory and other permits, licences and approvals and compliance with their terms; financing plans, financing availability and the anticipated sufficiency of NexGen’s financial resources; future uranium supply and demand, nuclear generating capacity, energy demand, market conditions and uranium market deficits; the anticipated environmental performance and effects of the Rook I Project, including the operation and performance of the Underground Tailings Management Facility and other environmental infrastructure; anticipated employment, procurement, economic, community and Indigenous-partnership benefits; forward-looking comparative, ranking, market-share, production and supply claims; forward-looking estimates of homes powered, emissions avoided, economic contributions and other impact or equivalency measures; and other future events, results, plans, objectives, expectations and intentions described on this website.

Generally, but not always, forward-looking information can be identified by the use of words such as “plans”, “expects”, “is expected”, “budget”, “scheduled”, “estimates”, “forecasts”, “intends”, “anticipates”, “believes”, “projects”, “targets”, “assumes”, “potential”, “could”, “may”, “would”, “should” or “will”, or the negative connotation of those terms, variations of those words and phrases or statements that certain actions, events or results may, could, would, should or will be taken, occur or be achieved. Statements relating to mineral resources are deemed to be forward-looking information, as they involve the implied assessment that, based on certain estimates and assumptions, the mineral resources described can be profitably produced in the future.

Forward-looking information is based on the then-current expectations, beliefs, assumptions, estimates and forecasts of NexGen and its management about NexGen’s business and the industry and markets in which it operates. Forward-looking information is made based upon numerous assumptions, including, among others, that the mineral reserve and mineral resource estimates and the key assumptions and parameters on which those estimates are based are as set out in NexGen’s applicable public disclosure and the technical report for the Rook I Project; that the current mineral reserves, mineral resources, mine plan and economic analysis for the Rook I Project remain those set out in the Rook I FS Technical Report defined below; that the results of planned exploration and development activities will be as anticipated and on time; that drill results and other geological information will be interpreted accurately; that uranium prices, exchange rates, inflation, capital costs, operating costs, sustaining capital, labour, equipment, materials, energy, reagents, transportation, taxes, royalties, closure costs and other project inputs will be consistent with the assumptions used in the applicable estimates, forecasts, projections and sensitivities; that plans for the development, construction, commissioning and operation of the Rook I Project will proceed as anticipated without changes in project parameters that would materially adversely affect the Rook I Project; that the Rook I Project will achieve the planned throughput, grade, recovery and production levels; that financing will be available if and when needed and on reasonable terms; that third-party contractors, equipment, supplies, labour and governmental, regulatory, Indigenous and other approvals required to conduct NexGen’s planned activities and advance, construct, commission and operate the Rook I Project will be available or obtained on reasonable terms and in a timely manner; that uranium demand, contracting activity, nuclear-generating capacity and other market conditions will develop as anticipated; that third-party information, forecasts and data used in comparative, market and impact information are accurate, complete and applicable for the purposes for which they are used; that the production premises, comparator groups, periods and calculation methodologies used in comparative, market, economic and impact information are appropriate; and that general business, economic, competitive, social and political conditions will not change in a material adverse manner. Although the assumptions made by the Company in providing forward-looking information are considered reasonable by management at the time, there can be no assurance that those assumptions will prove to be accurate.

Forward-looking information also involves known and unknown risks, uncertainties and other factors which may cause actual results, performance or achievements of NexGen to differ materially from any projections of results, performance or achievements expressed or implied by such forward-looking information, including, among others, negative operating cash flow and dependence on third-party financing; uncertainty regarding the availability, timing and terms of additional financing; the risk that pending or future assay results will not confirm previously announced preliminary results; the imprecision of mineral reserve and mineral resource estimates; the risk that actual exploration results will differ from those anticipated or will not support the estimation or expansion of mineral resources or mineral reserves; risks and uncertainties relating to economic evaluations, estimates, projections and sensitivity analyses; the risk that capital costs, operating costs, sustaining capital, closure costs, labour, equipment, materials, energy, reagents, transportation, taxes, royalties or other project inputs will increase more than expected; exploration and development risks; business-readiness and operating-mine transition risks; construction, engineering, procurement, contractor-performance, supply-chain, labour and inflationary risks; unexpected site, geotechnical, hydrogeological, environmental or operating conditions; delays, cost overruns, design changes, equipment failures or other difficulties in construction, shaft sinking, mine development, commissioning, ramp-up or operations; the risk that planned production, throughput, grade, recovery, schedule, mine life or economic results will not be achieved; the price of uranium and the appeal of alternative sources of energy; changes in exchange rates; the risk that actual reclamation, remediation or closure activities, costs or results will differ from expectations; the risk that changes to project parameters or plans as they continue to be refined will result in increased costs, delays or changes to expected project economics; delays in obtaining or maintaining governmental, regulatory or other permits, licences and approvals; risks relating to Indigenous title, rights, consultation, engagement, agreements and relationships; climate-change risks; environmental and other regulatory requirements; tariffs and trade restrictions; changes in laws, regulations, policies, regulatory interpretations or public perception; competition for resources; general inflationary pressures; the risk that anticipated environmental, employment, procurement, economic, community or Indigenous-partnership benefits will not be achieved; the risk that third-party market forecasts, sources or data are incomplete, inaccurate, outdated or not directly comparable; differences in definitions, methodologies, assumptions, comparator groups and periods used in comparative, market, ranking and impact information; reliance upon key management, other personnel and third-party contractors; deficiencies in the Company’s title to its properties; information-security and cybersecurity risks; uninsurable risks; failure to manage conflicts of interest; and those factors and other risks more fully described in NexGen’s Annual Information Form dated March 3, 2026 filed with the securities commissions of all provinces and territories of Canada and in NexGen’s Form 40-F filed with the United States Securities and Exchange Commission, which are available on SEDAR+ at www.sedarplus.ca and EDGAR at www.sec.gov.

Certain capital-cost information and uranium-price sensitivities referred to on this website, including the C$2.2 billion capital-cost figure and US$95/lb uranium-price sensitivity presented on the Rook I page, are based on internally prepared management estimates and interim cost-trend information. The US$95/lb uranium-price sensitivity is provided for illustrative sensitivity purposes only. This information should not be interpreted as replacing, amending or updating the Rook I FS Technical Report, or as representing a new or revised life-of-mine plan or base case, an updated capital-cost estimate or an updated economic analysis. The current mine plan and economic analysis remain those contained in the Rook I FS Technical Report.

Although the Company has attempted to identify important factors that could cause actual results to differ materially from those contained in or implied by forward-looking information, there may be other factors that cause results not to be as anticipated, estimated or intended. There can be no assurance that forward-looking information will prove to be accurate, as actual results and future events could differ materially from those anticipated, estimated or intended. Accordingly, readers should not place undue reliance on forward-looking information. The Company undertakes no obligation to update or reissue forward-looking information as a result of new information or events except as required by applicable securities laws.

Mineral Reserves and Mineral Resources

This website includes Mineral Reserve and Mineral Resource classification terms that comply with reporting standards in Canada, and the Mineral Reserve and Mineral Resource estimates are made in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”). NI 43-101 establishes standards for all public disclosure an issuer makes of scientific and technical information concerning mineral projects. These standards differ from the requirements of the United States Securities and Exchange Commission (“SEC”) applicable to domestic United States reporting companies. Consequently, Mineral Reserve and Mineral Resource information included on this website may not be comparable to similar information disclosed by domestic United States reporting companies subject to SEC reporting and disclosure requirements. Accordingly, information concerning mineral deposits set forth on this website may not be comparable with information made public by companies that report in accordance with United States standards.

The Arrow Mineral Reserves are included in the reported Arrow Mineral Resources. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. Inferred Mineral Resources are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as Mineral Reserves, and there is no certainty that further exploration will result in an Inferred Mineral Resource being upgraded to an Indicated or Measured Mineral Resource.

Scientific and Technical Information

The current Mineral Reserve and Mineral Resource estimates, mine plan, production profile and economic analysis for the Rook I Project disclosed on this website are derived from the Company’s independent feasibility study entitled Arrow Deposit, Rook I Project, Saskatchewan, NI 43-101 Technical Report on Feasibility Study, dated March 5, 2021, as amended and restated on March 10, 2021 (the “Rook I FS Technical Report” or the “FS”).

The Rook I FS Technical Report is available under the Company’s profile on SEDAR+ and EDGAR. For further information concerning the Rook I Project, including the assumptions, parameters and methods used to estimate its Mineral Reserves and Mineral Resources and the assumptions underlying the mine plan, production profile and economic analysis, readers should refer to the Rook I FS Technical Report.

Scientific and technical information concerning subsequent exploration activities, exploration results, construction activities and other developments is derived from the Company’s applicable public disclosure, including the Company’s most recently filed Annual Information Form, management’s discussion and analysis and applicable news releases, which are also available under the Company’s profile on SEDAR+ and EDGAR.

No Mineral Resources or Mineral Reserves have been estimated for Patterson Corridor East, and Patterson Corridor East has not been subject to an economic analysis. Patterson Corridor East exploration results are not included in the Mineral Resource estimates, Mineral Reserve estimates, mine plan, mine life, production profile or economic analysis contained in the Rook I FS Technical Report. There is no certainty that further exploration will result in the estimation of Mineral Resources or Mineral Reserves.

The scientific and technical information concerning operational matters on this website has been reviewed and approved by Mr. Simon Allard, P.Eng., Vice President, Commercial of NexGen. The scientific and technical information concerning exploration matters on this website has been reviewed and approved by Mr. Jason Craven, P.Geo., Vice President, Exploration of NexGen. Each of Mr. Allard and Mr. Craven is a “qualified person” for the purposes of NI 43-101.