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LocationWestern AustraliaCameco's share100%Mine typeOpen pitEstimated resources128.1 million lbs (measured and indicated)Average ore grade0.15% U3O8ProductUranium concentratesDiscovered1972Development ProgressWe believe that we have some of the best undeveloped uranium projects in the world. However, our current focus is on producing from our tier-one uranium assets at a pace aligned with our contract portfolio and market opportunities. No work is planned at Yeelirrie in 2026.Environmental AssessmentsA number of studies have been completed to evaluate the potential effects during the construction, operation, and decommissioning of the Yeelirrie project.Learn more at camecoaustralia.com

2025 Q4 UpdateProductionTotal production from JV Inkai in 2025 was 8.4 million pounds (3.7 million pounds our share) compared to 7.8 million pounds (3.6 million pounds our share) in 2024. During 2025, we received shipments containing the remainder of our share of 2024 production, about 0.9 million pounds, and the entire 3.7 million pounds of our share of Inkai’s 2025 production. On December 31, 2024, we were unexpectedly informed that KAP, as majority owner and controlling partner of the joint venture, had directed JV Inkai to suspend production activity as of January 1, 2025. The suspension was implemented pending approval by Kazakhstan’s Ministry of Energy of an extension to submit an updated Project for Uranium Deposit Development documentation. When the extension had not yet been granted at 2024 year-end as expected, KAP made the decision to halt production in order to avoid potential violation of Kazakhstan legislation. The extension was approved and JV Inkai resumed production on January 23, 2025. Subsequently, Inkai adjusted its mining plan and successfully managed its production, reaching the target of 8.4 million pounds in 2025.Delivery ScheduleThe geopolitical situation continues to cause transportation risks in the region. We could continue to experience delays in our expected Inkai deliveries. To mitigate this risk, we have inventory, long-term purchase agreements and loan arrangements in place we can draw on. Depending on when we receive shipments of our share of Inkai’s production, our share of earnings from this equity-accounted investee and the timing of the receipt of our share of dividends from the joint venture may be impacted.See full Quarterly ReportEnvironment & SafetyWorker safety, environmental monitoring and proper decommissioning after project completion are of the utmost importance to Cameco.See moreReserves & ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.See more

US ISR OperationsAs a result of our 2016 decision, commercial production at the US operations ceased in 2018. We expect ongoing cash and non-cash care and maintenance costs to range between US$14 million and US$15 million for 2026.See full Quarterly ReportEnvironment & SafetyWorker safety, environmental monitoring and proper decommissioning after project completion are of the utmost importance to Cameco.See moreReserves & ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.See more

Measured and Indicated As of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding) MeasuredIndicatedTotal Measured and IndicatedPropertyTonnesGrade%U3O8Content(lbs U3O8)TonnesGrade%U3O8Content(lbs U3O8)Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake82.35.09.1153.85.0717.226.314.3Kintyre   3,897.70.6253.553.553.5McArthur River72.02.283.662.62.223.16.74.7Millennium   1,442.62.3975.975.953.0Rabbit Lake   1,836.50.9538.638.638.6Tamarack   183.84.4217.917.910.3Yeelirrie27,172.90.1695.912,178.30.1232.2128.1128.1Crow Butte1,558.10.196.6939.30.357.213.813.8Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.11,438.40.092.83.93.9Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,892.5-184.4107,462.3-319.7504.0404.0Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingInferredAs of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding)PropertyTonnesGrade%U3O8Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake163.45.5520.010.9Fox Lake386.77.9968.153.3Kintyre517.10.536.06.0McArthur River36.40.532.41.7Millennium412.43.1929.020.2Rabbit Lake2,460.90.6233.733.7Tamarack45.61.021.00.6Crow Butte531.40.161.81.8Gas Hills-Peach3,307.50.086.06.0Inkai33,742.20.0323.38.9North Butte-Brown Ranch294.50.070.40.4Ruby Ranch56.20.140.20.2Shirley Basin508.00.101.11.1Smith Ranch-Highland6,861.00.057.77.7Total49,323.5-201.3153.2Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingMineral Reserves and ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.We have interests in a number of uranium properties. The tables in this section show the estimates of the proven and probable mineral reserves, and measured, indicated, and inferred mineral resources at those properties. However, only three of the properties listed in those tables are material uranium properties for us: McArthur River/Key Lake, Cigar Lake and Inkai. Mineral reserves and resources are all reported as of December 31, 2025.We estimate and disclose mineral reserves and resources in five categories, using the definition standards adopted by the Canadian Institute of Mining, Metallurgy and Petroleum Council, and in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (NI 43-101), developed by the Canadian Securities Administrators.  About mineral resourcesMineral resources do not have to demonstrate economic viability but have reasonable prospects for eventual economic extraction. They fall into three categories: measured, indicated and inferred. Our reported mineral resources are exclusive of mineral reserves.measured and indicated mineral resources can be estimated with sufficient confidence to allow the appropriate application of technical, economic, marketing, legal, and sustainability factors to support evaluation of the economic viability of the depositmeasured resources: we can confirm both geological and grade continuity to support detailed mine planningindicated resources: we can reasonably assume geological and grade continuity to support mine planninginferred mineral resources are estimated using limited geological evidence and sampling information. We do not have enough confidence to evaluate their economic viability in a meaningful way. You should not assume that all or any part of an inferred mineral resource will be upgraded to an indicated or measured mineral resource, but it is reasonably expected that the majority of inferred mineral resources could be upgraded to indicated mineral resources with continued exploration.Our share of uranium in the following mineral resource tables is based on our respective ownership interests. Reported mineral resources have not demonstrated economic viability.About mineral reservesMineral reserves are the economically mineable part of measured and/or indicated mineral resources demonstrated by at least a preliminary feasibility study. The reference point at which mineral reserves are defined is the point where the ore is delivered to the processing plant, except for ISR operations where the reference point is where the mineralization occurs under the existing or planned wellfield patterns. Mineral reserves fall into two categories:proven reserves: the economically mineable part of a measured resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a high degree of confidenceprobable reserves: the economically mineable part of a measured and/or indicated resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a degree of confidence lower than that applying to proven reserves For properties where we are the operator, we use current geological models, an average uranium price of $63 (US) per pound U3O8, and current or projected operating costs and mine plans to report our mineral reserves, allowing for dilution and mining losses. We apply our standard data verification process for every estimate. For properties in which we have an interest but are not the operator, we will take reasonable steps to ensure that the reserve and resource estimates that we report are reliable.Our share of uranium in the mineral reserves table below is based on our respective ownership interests.Changes this year Our share of proven and probable mineral reserves decreased from 457 million pounds U3O8 at the end of 2024 to 433 million pounds at the end of 2025. The change was primarily the result of production at Cigar Lake, Inkai and McArthur River, which removed 25 million pounds of proven and probable reserves from our mineral inventory slightly offset by other adjustments based on the mineral reserve estimate updates at Cigar Lake, McArthur River and Inkai.Our share of measured and indicated mineral resources decreased from 408 million pounds U3O8 at the end of 2024 to 404 million pounds at the end of 2025. Our share of inferred mineral resources decreased from 153 million pounds U3O8 to 152 million pounds U3O8. Qualified personsThe technical and scientific information discussed on this page for our material properties (McArthur River/Key Lake, Cigar Lake and Inkai) was approved by the following individuals who are qualified persons for the purposes of NI 43-101:McArthur River/Key LakeGreg Murdock, general manager, McArthur River, CamecoDaley McIntyre, general manager, Key Lake, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoCigar LakeKirk Lamont, general manager, /Cigar Lake, CamecoScott Bishop, director, technical services, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoInkaiAlain D. Renaud, principal resource geologist, technical services, CamecoScott Bishop, director, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoSergey Ivanov, deputy director general, technical services, Cameco Kazakhstan LLPImportant information about mineral reserve and resource estimatesAlthough we have carefully prepared and verified the mineral reserve and resource figures in this document, the figures are estimates, based in part on forward-looking information.Estimates are based on knowledge, mining experience, analysis of drilling results, the quality of available data and management’s best judgment. They are, however, imprecise by nature, may change over time, and include many variables and assumptions, including:geological interpretationextraction planscommodity prices and currency exchange ratesrecovery ratesoperating and capital costsThere is no assurance that the indicated levels of uranium will be produced, and we may have to re-estimate our mineral reserves based on actual production experience. Changes in the price of uranium, production costs or recovery rates could make it unprofitable for us to operate or develop a particular site or sites for a period of time. See page 2 of our 2025 Q4 MD&A for information about forward-looking information.Please see our mineral reserves and resources section of our most recent annual information form for the specific assumptions, parameters and methods used for McArthur River, Inkai and Cigar Lake mineral reserve and resource estimates. Important information for US investorsWe present information about mineralization, mineral reserves and resources as required by National Instrument 43-101 – Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators (NI 43-101), in accordance with applicable Canadian securities laws. As a foreign private issuer filing reports with the US Securities and Exchange Commission (SEC) under the Multijurisdictional Disclosure System, we are not required to comply with the SEC’s disclosure requirements relating to mining properties. Investors in the United States should be aware that the disclosure requirements of NI 43-101 are different from those under applicable SEC rules, and the information that we present concerning mineralization, mineral reserves and resources may not be comparable to information made public by companies that comply with the SEC’s reporting and disclosure requirements for mining companies.

2025 Q4 UpdateThe site remained in a safe state of care and maintenance throughout 2025. While in standby, we continue to evaluate our options to minimize care and maintenance costs. We expect standby operating costs in care and maintenance to range between $44 million and $47 million in 2026, an increase from 2025 attributed to project work related to infrastructure maintenance. See full Quarterly ReportEnvironment & SafetyWorker safety, environmental monitoring and proper decommissioning after project completion are of the utmost importance to Cameco.See moreReserves & ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.See more

2025 Q4 UpdateProductionMcArthur River ProductionCameco's Share (million lb)Three months ended December 31Year ended December 31  20252024202520242025Plan2026 Plan23.33.610.514.29.8 to 10.5110.0 to 11.51 In August, we changed our outlook for production at McArthur River/Key Lake to produce between 14 million and 15 million pounds (100% basis) in 2025 (previously expected 18 million pounds).2 Production ranges are rounded to the nearest half-million. Total packaged production from McArthur River and Key Lake in 2025 was 15.1 million pounds (10.5 million pounds our share), compared to 20.3 million pounds (14.2 million pounds our share) in 2024. Planned production was not achieved due to a shortfall in mine production at McArthur River as disclosed on August 28, 2025.The McArthur River mine was unable to fully mitigate the impacts of the delayed development and ground freezing in new mining zones. The mine’s performance was also impacted by availability of equipment and certain workforce skills.The Key Lake mill saw notable improvements in its operational performance in 2025, with the site becoming more familiar and experienced with new equipment and control system upgrades. In addition, the systematic understanding of process bottlenecks and efforts to remove or decrease their impacts allowed Key Lake to optimize the mill throughput rates. Despite these improvements, overall production for the year was constrained by a six-week unplanned shutdown in the fall of 2025, resulting from a lack of ore feed from McArthur River, which limited the mill’s ability to consistently operate at planned rates and ultimately impacted the achievement of production targets.ExplorationUnderground exploration at McArthur River continued in 2025 with the focus areas being in-fill drilling of zones A and B as well as surface exploration drilling on northern brownfield drill targets.Planning for the futureWe plan to produce from 14 million to 16.5 million pounds (100% basis) in 2026; our share is approximately 10.0 million to 11.5 million pounds. The production rate is currently constrained by limited ore feed supply as a result of delays in new mining areas at McArthur River. In 2026, we expect to bring zone 1 into production which will notably improve the number of mining fronts available. In addition, we will continue to advance zone 4 south development while adding to our workforce and replacing mobile equipment. We also plan to continue with our underground exploration activities in 2026.Labour RelationsThe collective agreement with the United Steelworkers Local 8914 expired in December 2025. As such, there is a potential risk of a labour dispute impact in 2026 if a new contract agreement cannot be reached.See full Quarterly ReportEnvironment & SafetyWorker safety, environmental monitoring and proper decommissioning, after mining is completed, are of the utmost importance to Cameco.See moreReserves & ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.See more

SafetyThe Inkai operation has an excellent safety record. The operation has a management system to identify, document and address risks and engage all workers and managers in development of a strong safety culture. The safety management system is certified to the international OHSAS:18001 standard and is focused on driving continual improvement in safety performance of employees and contractors.Radiation ProtectionRadiation risks are effectively managed at Inkai through a formal radiation protection program and dedicated personnel who ensure that doses to workers are as low as reasonably achievable. The program ensures that radiation protection is considered in the physical design of all facilities and operating procedures. It also provides for systematic monitoring of radiation in work areas and tracking the exposures of individual workers using a combination of monitoring devices and health testing. Radiation exposures at Inkai are far below the regulated limits.Environmental ProtectionEnvironmental protection at Inkai is managed through an ISO 14001-certified environmental management system. The system provides for systematic identification and mitigation of environmental risks and reduction and effective management of waste. Inkai uses the in situ recovery (ISR) mining method which produces no tailings or waste rock and involves minimal surface disturbance. Uranium is extracted from underground by pumping a mild acid solution into the ore zone. The uranium is freed from a sandstone formation and pumped to the surface for processing.Environmental MonitoringMonitor wells are installed around the ore zones to allow testing of groundwater quality around the ore zones.Waste ManagementThe situ recovery (ISR) mining method employed at Inkai produces no tailings or waste rock. Water used in the process is recycled. Plastic, cardboard, scrap metal and other waste materials are sent for recycling to external companies.DecommissioningDetailed plans are being developed to provide for decommissioning of the Inkai mine. Once operations are complete in a wellfield, the brackish groundwater in the deep sandstone aquifer being mined recovers by natural attenuation. All piping and other infrastructure is removed and surface lands are restored to their original state.Environmental AssessmentAll new mining developments and significant changes to existing operations are subject to environmental review and licensing by Kazakh regulatory authorities.Regulatory OversightThe Inkai operation is overseen by a number of Kazakh regulatory authorities, including the Atomic Energy Committee, the Ministry of Environmental Protection, the Ministry of Emergency Situations and the Ministry of Labour and Social Protection.

Our relationships with our workforce, Indigenous Peoples, and local communities are fundamental to our success. We aim to build a workforce that is dedicated to continuous improvement and shares our values.The following are highlights of selected social topics discussed in our 2024 Sustainability Report. Please see the report for more information or Our Performance for all indicator results.

LocationSaskatchewan, CanadaCameco's share69.9%Mine typeUndergroundEstimated resources (Cameco's share)53.0 million lbs (indicated), average grade U3O8: 2.39%20.2 million lbs (inferred), average grade U3O8: 3.19%ProductUranium concentratesDiscovered2000Other possible featuresOff-site processingEmployment: about 150 at full productionEstimated life of mine: 10 yearsDevelopment ProgressWe believe that we have some of the best undeveloped uranium projects in the world. However, our current focus is on producing from our tier-one uranium assets at a pace aligned with our contract portfolio and market opportunities. No work is planned at Millennium in 2026.Environmental AssessmentA number of studies have been completed to evaluate the potential effects during the construction, operation, and decommissioning of the Millennium project.See more

US ISR OperationsAs a result of our 2016 decision, commercial production at the US operations ceased in 2018. We expect ongoing cash and non-cash care and maintenance costs to range between US$14 million and US$15 million for 2026.See full Quarterly ReportEnvironment & SafetyWorker safety, environmental monitoring and proper decommissioning after project completion are of the utmost importance to Cameco.See moreReserves & ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.See more