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Measured and Indicated As of December 31, 2024(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 Lake75.54.888.1141.34.9515.423.612.9Kintyre   3,897.70.6253.553.553.5McArthur River71.82.283.660.32.313.16.74.7Millenium   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 Butte1,558.10.196.6939.30.357.313.913.9Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.15,530.30.078.49.49.4Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,885.6–183.4111,550.5–323.6507.0408.2Note 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 roundingInferredAs of December 31, 2024(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 River36.42.952.41.7Millenium412.43.1929.020.2Rabbit Lake2,460.90.6233.733.7Tamarack45.61.021.00.6Crow Butte531.40.161.81.8Gas Hills-Peach3,307.50.086.06.0Inkai33,742.20.0322.38.9North Butte-Brown Ranch294.50.070.40.4Ruby Ranch56.20.140.20.2Shirley Basin508.00.101.11.1Smith Ranch-Highland6,861.00.057.77.7Total49,323.5–199.8152.6Note 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, 2024.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, environmental, social and governmental 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 reservesWe 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 Cameco has an interest but is 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 485 million pounds U3O8 at the end of 2023, to 457 million pounds at the end of 2024. The change was primarily the result of:production at Cigar Lake, Inkai and McArthur River, which removed 27 million pounds of proven and probable reserves from our mineral inventory.The remaining changes are attributable to 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 409 million pounds U3O8 at the end of 2023 to 408 million pounds at the end of 2024. Our share of inferred mineral resources remained unchanged at 153 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, Cameco​Biman 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 2024 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.

Measured and Indicated As of December 31, 2024(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 Lake75.54.888.1141.34.9515.423.612.9Kintyre   3,897.70.6253.553.553.5McArthur River71.82.283.660.32.313.16.74.7Millenium   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 Butte1,558.10.196.6939.30.357.313.913.9Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.15,530.30.078.49.49.4Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,885.6–183.4111,550.5–323.6507.0408.2Note 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 roundingInferredAs of December 31, 2024(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 River36.42.952.41.7Millenium412.43.1929.020.2Rabbit Lake2,460.90.6233.733.7Tamarack45.61.021.00.6Crow Butte531.40.161.81.8Gas Hills-Peach3,307.50.086.06.0Inkai33,742.20.0322.38.9North Butte-Brown Ranch294.50.070.40.4Ruby Ranch56.20.140.20.2Shirley Basin508.00.101.11.1Smith Ranch-Highland6,861.00.057.77.7Total49,323.5–199.8152.6Note 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, 2024.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, environmental, social and governmental 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 reservesWe 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 Cameco has an interest but is 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 485 million pounds U3O8 at the end of 2023, to 457 million pounds at the end of 2024. The change was primarily the result of:production at Cigar Lake, Inkai and McArthur River, which removed 27 million pounds of proven and probable reserves from our mineral inventory.The remaining changes are attributable to 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 409 million pounds U3O8 at the end of 2023 to 408 million pounds at the end of 2024. Our share of inferred mineral resources remained unchanged at 153 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, Cameco​Biman 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 2024 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.

Measured and Indicated As of December 31, 2024(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 Lake75.54.888.1141.34.9515.423.612.9Kintyre   3,897.70.6253.553.553.5McArthur River71.82.283.660.32.313.16.74.7Millenium   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 Butte1,558.10.196.6939.30.357.313.913.9Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.15,530.30.078.49.49.4Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,885.6–183.4111,550.5–323.6507.0408.2Note 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 roundingInferredAs of December 31, 2024(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 River36.42.952.41.7Millenium412.43.1929.020.2Rabbit Lake2,460.90.6233.733.7Tamarack45.61.021.00.6Crow Butte531.40.161.81.8Gas Hills-Peach3,307.50.086.06.0Inkai33,742.20.0322.38.9North Butte-Brown Ranch294.50.070.40.4Ruby Ranch56.20.140.20.2Shirley Basin508.00.101.11.1Smith Ranch-Highland6,861.00.057.77.7Total49,323.5–199.8152.6Note 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, 2024.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, environmental, social and governmental 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 reservesWe 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 Cameco has an interest but is 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 485 million pounds U3O8 at the end of 2023, to 457 million pounds at the end of 2024. The change was primarily the result of:production at Cigar Lake, Inkai and McArthur River, which removed 27 million pounds of proven and probable reserves from our mineral inventory.The remaining changes are attributable to 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 409 million pounds U3O8 at the end of 2023 to 408 million pounds at the end of 2024. Our share of inferred mineral resources remained unchanged at 153 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, Cameco​Biman 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 2024 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 Q3 UpdateProductionMcArthur River ProductionCameco's Share (million lbs)Three months ended September 30Six months ended September 30 20252024Change20252024Change2025 Plan2.22.8(21)%7.210.6(32)%9.8 to 10.51 As announced in August, our outlook for production from McArthur River/Key Lake has changed. We now expect to produce between 14 million and 15 million pounds (100% basis) in 2025 (previously expected 18 million pounds).In the third quarter of 2025, total packaged production from McArthur River and Key Lake was 3.2 million pounds (2.2 million pounds our share) compared to 4 million pounds (2.8 million pounds our share) in the third quarter of 2024. In the first nine months of the year, total packaged production from McArthur River and Key Lake was 10.3 million pounds (7.2 million pounds our share) compared to 15.2 million pounds (10.6 million pounds our share) in the first nine months of 2024. The lower packaged production is primarily due to the delays we have experienced in transitioning into new mining areas at McArthur River in 2025. As a result of these development delays at McArthur River, the Key Lake mill was shut down from September 3 through October 17, impacting production in the third quarter and the first nine months, and resulting in lower expected production for 2025. As announced on August 28, 2025, we now expect 2025 packaged production of 14 million to 15 million pounds (9.8 to 10.5 million pounds our share).  Labour RelationsThe collective agreement with the United Steelworkers Local 8914 expires in December 2025. As such, we expect the impact risk of a labour dispute, if it were to occur, to be minimal in 2025.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

Cameco is one of the largest global providers of the uranium fuel needed to power a safe, secure energy future.Our competitive position is based on our controlling ownership of the world’s largest high-grade reserves and low-cost operations, as well as significant investments across the nuclear fuel cycle, including ownership interests in Westinghouse Electric Company and Global Laser Enrichment. Utilities around the world rely on Cameco to provide global nuclear fuel solutions for the generation of safe, reliable, carbon-free nuclear power.We are proud to be one of Canada’s largest employers of Indigenous people, and our land holdings, including exploration, span about 1.8 million acres, the majority near our existing operations in northern Saskatchewan. Our head office is in Saskatoon, Saskatchewan, Canada.

We recognize and embrace our responsibility to minimize our impacts on air, land, and water and to safeguard the biodiversity of surrounding ecosystems.The following are highlights of selected priority environmental topics. Please see our 2024 Sustainability Report for more information or Our Performance for all indicator results. WaterResponsible water management is critical to our business. We recognize the importance of preserving this resource for the Indigenous Peoples and local communities we share it with today. We work continuously with regulators, governments, researchers, and communities to understand possible impacts, develop best practices, and make changes that mitigate potential impacts on the environment. At our sites and facilities, we have robust water management and monitoring programs that apply to all withdrawals and discharges, and we tailor our water management practices to local uses and conditions.Water sources and usesThe vast majority of water (groundwater, surface water, or precipitation) managed by our Saskatchewan facilities is not intentionally withdrawn for mining use but instead intercepted as part of our mining operations through mine dewatering or from the operation of our tailings management facilities. Where possible, we use this intercepted water to support our operational water requirements.Water discharges At Cameco, we carefully manage our treated water discharges to keep potential risks to human health and the environment as low as reasonably achievable and to comply with applicable legal and regulatory requirements. To protect people and the environment, we have implemented management tools consistent with our overall management approach, which include:inflow reductionwater segregationwater treatmentDischarge monitoringWe have monitoring programs to verify that human health and the environment remain protected in the vicinity of our operations. We adhere to regulatory requirements from the Canadian Nuclear Safety Commission, the Saskatchewan Ministry of Environment, and Environment and Climate Change Canada.Watershed stewardshipAs part of our environmental monitoring programs, we take more than 22,000 samples related to water quality each year. We collect water samples at or immediately downstream of our operations (near-field), in close proximities to our operations (mid-field), and at locations at a further distance (five to ten kilometres) from our operations (far-field). These samples are sent for testing for different chemicals and other indicators of quality to both internal laboratories and an accredited third-party facility. Learn more about our watershed stewardshipTailings ManagementTailings and waste rock are an inevitable byproduct of most mining activities. Responsible and safe management of mining waste streams is critical to protecting the environment as well as the safety of our workers, operations and communities.  To strengthen our tailings management approach, we seek to apply lessons learned from industry incidents and are committed to continuous improvement. Milling of uranium ore produces tailings, which are primarily composed of the residual rock left after the uranium is recovered, mineral precipitates, and minor amounts of processing chemicals. These tailings are safely stored on-site within engineered tailings management facilities. The annual tonnage of tailings produced varies and is dependent on the ore grade and the production rate. The high uranium grade of our mines in northern Saskatchewan means we obtain more uranium per tonne of rock processed than low grade facilities, resulting in lower amounts of tailings per unit of uranium produced.Tailings management is relevant only to our Canadian operations because the in situ recovery method used in our US operations does not produce tailings or waste rock. We have four tailings facilities in Saskatchewan, two at our Key Lake site and two at our Rabbit Lake site. Both Key Lake and Rabbit Lake have one active in-pit tailings facility (in-pit facility) and one above-ground tailings management facility (above-ground tailings facility).We employ broad, risk-based practices to effectively manage our tailings and mine waste storage facilities. We have accountability at the highest level of the organization, and systems and procedures that follow best practices contained in industry recognized standards. Learn more about our tailings management practicesGHG EmissionsAt Cameco, we recognize the critical nature of the fight against climate change and that there are risks and opportunities associated with climate change and the energy transition as we seek to achieve our strategic plan.  We are committed to addressing these risks and taking advantage of the opportunities in a manner that we expect to add long-term value for our stakeholders.Our GHG emissions are directly related to the type and amount of energy we consume. Cameco quantifies emissions following the globally recognized GHG Protocol Corporate Standard.Scope 1~131,381 tCO2eOur Scope 1 emissions are primarily associated with the consumption of propane and natural gas for heating. We also use diesel and gasoline to operate heavy-duty and light vehicles across our operations, and relatively small quantities of diesel for back-up power generation. We release small quantities of GHG emissions from chemical processes during milling and from Cameco operated landfills.Scope 2~178,306 tCO2eAll Scope 2 emissions arise from electricity consumption and correlate to the emissions intensity of grid-supplied electricity in the regions we operate. Our main source of power for our northern Saskatchewan operations is hydroelectric. However, our location-based Scope 2 emissions use a single emissions factor that reflects the energy mix from the entire provincial grid in Saskatchewan and Ontario (data in the performance table).Scope 3~620,000 tCO2eScope 3 emissions are not covered in Scope 1 or 2 and result from activities that occur in our value chain. Building on our work from last year, where we reported our total Scope 3 emissions in our 2023 Sustainability Report, we are now reporting our Scope 3 emissions broken down by category as noted below. Scope 3 Emissions by Category   Our GHG reduction targetOur 30 by 30 reduction target means that we will work to permanently reduce our Scope 1 and Scope 2 GHG emissions by 155,000 tCO₂e across our operated facilities by 2030. Under this target, we will also strive to achieve a minimum reduction of 30,000 tCO₂e from Scope 1 emissions specifically. This sub-target demonstrates our commitment to reducing the direct carbon footprint of Cameco facilities and maintain alignment with facility-based emissions reductions required by regulators. Learn more about our GHG emissions and energy useDecommissioningOur commitment to protecting the environment and the needs of the communities around our operations extends to the full life-cycle of our mines and facilities. This includes planning for decommissioning and preparing our sites for permanent closure. Conceptual plans for each site describes activities required to reclaim the site to defined final end-state objectives, after the operating life of a facility. The plan includes a preliminary cost estimate for labour, materials, equipment, waste management, regulatory approvals, monitoring, and administration to carry out the plan.At the end of 2024, our estimated future decommissioning and reclamation costs (total and undiscounted) for our assets were approximately $1.38 billion, with some revised estimates still subject to regulatory approval. We have recorded accounting provisions for the discounted value of these estimates, and every quarter, we update these estimates based on new cash flow estimates, discount, and inflation rates. To verify we can pay for these future obligations, we have financial assurances of $1.13 billion (in the form of letters of credit or surety bonds to satisfy current regulatory requirements), which is based on previously approved preliminary decommissioning estimates and will increase once the regulator approves all revised estimates and confirms the value of financial assurances required. The expected timing for these costs is based on each mine or fuel services facility’s expected operating life. Our required costs for decommissioning and reclamation in each of the next five years are not expected to be material. Proactive reclamationIf part of an active site is ready for reclamation before the full site reaches the end of its life, we can proceed proactively with reclamation work on that area. Some of the projects we have undertaken in the last few years include:Water restoration in the U.S.In 2024, one mine unit had a final restoration report and decommissioning plan submitted. Five mine units are undergoing reverse osmosis treatment, six mine units are currently in stability, and two mine units are preparing to enter the stability stage.Waste rock pile revegetation at Key LakeThe Key Lake operation continues to undergo progressive reclamation. At one of Key Lake’s waste rock piles, we have been successful at revegetating a portion of a covered pile through the application of local lake bottom organic sediments as a nutrient source and seed bank to establish shrubs, bushes, and trees. Learn more2024 Sustainability Report - EnvironmentOur Performance for all indicator results.Environment and safety at our uranium operationsEnvironment and safety at our fuel services businessCigar LakeMcArthur River/Key LakeRabbit LakeBlind River RefineryPort Hope Conversion FacilityCameco Fuel Manufacturing

A market in transitionIn 2024, geopolitical uncertainty and heightened concerns about energy security, national security, and climate change continued to improve the demand and supply fundamentals for the nuclear power industry and the fuel cycle that is required to support it. Increasingly, countries and companies around the globe are recognizing the critical role nuclear power must play in providing carbon-free and secure baseload power. This was evidenced at the 29th Conference of Parties (COP29), where a total of 31 countries have now signed the declaration to triple nuclear energy capacity by 2050. This growing support has led to a rise in demand with closed reactors returning to service, reactor life extensions being sought and approved, and numerous commitments and plans are advancing for the construction of new nuclear capacity. In addition, there is increasing interest in small modular reactors (SMR), including smaller versions of existing technology and advanced technology designs, with companies in energy intensive sectors looking to nuclear to help achieve their decarbonization plans. The potential expansion of the markets and use cases for nuclear energy could add significant demand in the decades to come.While demand continues to increase, future supply is not keeping pace. Heightened supply risk caused by growing geopolitical uncertainty, shrinking secondary supplies and a lack of investment in new capacity over the past decade has motivated utilities to evaluate their near-, mid- and long-term nuclear fuel supply chains. The uncertainty about where nuclear fuel supplies will come from to satisfy growing demand has led to significant long-term contracting activity in recent years. In 2024, about 119 million pounds of uranium was placed under long-term contracts by utilities. While the volume remains below replacement rate, this further increases the cumulative level of uncovered requirements in the decade to come, when primary supply is expected to be even more limited and uncertain, and secondary supply stacks have been drawn down. We expect continued competition to secure uranium, conversion services and enrichment services under long-term contracts with proven sustainable producers and suppliers who have a diversified portfolio of assets in geopolitically attractive jurisdictions, and on terms that help ensure a reliable supply is available to satisfy demand. Supply uncertaintyGeopolitical uncertainty, energy security, and national security are notable factors impacting security of supply in 2024. Geopolitical uncertainty is causing some utilities to seek nuclear fuel suppliers whose values are aligned with their own or whose origin of supply better protects them from potential interruptions, including from transportation challenges or the possible imposition of formal sanctions. Driven by the Russian invasion of Ukraine, the mine suspension in Niger, and supply chain challenges, particularly in Kazakhstan, many governments and utilities are re-examining procurement strategies that rely on nuclear fuel supplies from these jurisdictions. With the lack of investment over the past decade, there is growing uncertainty about where uranium will come from to satisfy growing demand, and utilities are becoming increasingly concerned about the availability of material to meet their long-term needs. Several uranium projects restarted in 2024 in support of increased demand, though delays and higher-than-expected production costs were a common theme.In addition, secondary supplies have diminished, and the material available in the spot market has thinned as producers and financial funds continue to purchase material. Despite the positive price trend in 2024, the deepening geopolitical uncertainty, sanctions and trade policy restrictions, and years of underinvestment in new uranium and fuel cycle service capacities, supply risk has shifted from producers to utilities. Durable demand growthThe benefits of nuclear energy have come clearly into focus, supporting a level of durability that, we believe, has not been previously seen. The durability is being driven not only by the geopolitical realignment in energy markets but also by a global focus on achieving the net-zero carbon targets set by countries and companies around the world.  Geopolitical uncertainty has deepened concerns about energy security and national security, highlighting the role of energy policy in balancing three main objectives: providing a reliable and secure baseload profile;providing an affordable, levelized cost profile;providing a clean emissions profile. Net-zero carbon targets are also turning global attention to a broader triple challenge: about one-third of the global population must be lifted out of energy poverty by improving access to clean and reliable baseload electricity;approximately 80% of the current global electricity grids that run on carbon-emitting sources of thermal power must be replaced with a carbon-free, reliable alternative;and global power grids must grow by electrifying industries, such as private and commercial transportation, and home and industrial heating, which today are largely powered with carbon-emitting sources of thermal energy. There is increasing recognition that nuclear power meets these objectives and has a key role to play in achieving energy security and decarbonization goals. The growth in demand is not just long-term and in the form of new builds, but medium-term in the form of reactor restarts and life extensions, and near-term with early reactor retirement plans being deferred or cancelled and new markets continuing to emerge. Long-term momentum remains very supportive with the installed base of nuclear capacity and an increasing focus on large-scale new build and the development of SMRs.The IEA World Energy Outlook 2024 predicts a 62% increase in electricity demand from 2023 to 2040, with a 95% increase predicted from 2023 to 2050. Future estimatesHistoric1990 100922010 215112022 291452023 29863203037489 204048409 205058352 According to the International Atomic Energy Agency (IAEA), globally, there are currently 439 operable reactors and 63 reactors under construction. Demand-related developments continue to suggest growing support for the nuclear industry, with 31 countries pledging to triple their nuclear power capacity by 2050.  Number of ReactorsChina29Asia10India6Africa & Middle East6Russia5Eastern Europe3Americas2UK2Supply-Demand: Putting it TogetherLike other commodities, the demand for uranium is cyclical. However, unlike other commodities, uranium is not traded in meaningful quantities on a commodity exchange. The uranium market is principally based on bilaterally negotiated long-term contracts covering the annual run-rate requirements of nuclear power plants, with a small spot market to serve discretionary demand. History demonstrates that in general, when prices are rising and high, uranium is perceived as scarce, and more contracting activity takes place with proven and reliable suppliers. The higher demand discovered during this contracting cycle drives investment in higher-cost sources of production, which due to lengthy development timelines, tend to miss the contracting cycle and ramp up after demand has already been won by proven producers. When prices are declining and low, there is no perceived urgency to contract, and contracting activity and investment in new supply dramatically decreases. After years of low prices, and a lack of investment in supply, and as the uncommitted material available in the spot market begins to thin, security-of-supply tends to overtake price concerns. Utilities typically re-enter the long-term contracting market to ensure they have a reliable future supply of uranium to run their reactors. Spot MarketLong Term MarketAverage Spot Price2004208418.620053625228.6720063520049.620072025099.2920084313061.5820095415046.0620105025046.8320115611256.3620124319348.42013502438.172014437733.212015498136.552016466025.64201748.173.121.78201888.589.924.59201963.395.825.64202094.557.429.962021102.4171.7935.28202260.85113.0049.81202355.03159.6062.51202446.37119.285.14UxC reports that over the last five years approximately 534 million pounds U3O8 equivalent have been locked-up in the long-term market, while approximately 798 million pounds U3O8 equivalent have been consumed in reactors. UxC estimates that cumulative uncovered requirements are about 2.1 billion pounds to the end of 2040. We believe this presents a substantial opportunity for proven and reliable suppliers with tier-one productive capacity and a record of honoring supply commitments.We will continue to take the actions we believe are necessary to position the company for long-term success, aligning our production decisions with customers’ needs under our contract portfolio. We will undertake contracting activity which is intended to ensure we have adequate protection while maintaining exposure to the benefits that come from having uncommitted, low-cost supply to place into a strengthening market. 

We are a pure-play investment in the growing demand for nuclear energy, focused on taking advantage of the near-, medium- and long-term growth occurring in our industry. We provide nuclear fuel and nuclear power products, services and technologies across the fuel and reactor life cycles, augmented by our investment in Westinghouse, that supports the generation of carbon-free, reliable, secure and affordable energy. Our strategy is set within the context of what we believe is a transitioning market environment. Increasing populations, a growing focus on electrification and decarbonization, and concerns about energy security and affordability are driving a global focus on tripling nuclear power capacity by 2050, which is expected to durably strengthen long-term fundamentals for our industry. Nuclear energy must be a central part of the solution to achieving energy growth and national security objectives, and helping the world shift to a low-carbon, climate resilient economy. It is an option that can provide the necessary power in a carbon-free, reliable and affordable manner.Our strategy is to capture full-cycle value by:remaining disciplined in our contracting activity, building a balanced portfolio in accordance with our contracting frameworkprofitably producing from our tier-one assets and aligning our production decisions in all segments of our business with our contract portfolio and customer needsbeing financially disciplined to allow us toexecute on our strategy invest in new opportunities that are expected to add long-term valueself-manage riskexploring other emerging opportunities within the nuclear power value chain that align with our commitment to manage our business responsibly and sustainably, contribute to decarbonization, and help to provide secure and affordable energy We expect our strategy will allow us to increase long-term value, and we will execute it with an emphasis on safety, people and the environment.Our vision – “Powering a secure energy future” – recognizes that we have an important role to play in achieving energy security, national security and climate security. Our uranium and fuel services are used around the world in the generation of safe, reliable, carbon-free, baseload nuclear power, which is crucial to energy security. In times of geopolitical uncertainty, a secure source of nuclear fuel is more important than ever as it also supports national security objectives. Additionally, Cameco supports climate security by enabling the generation of carbon-free nuclear power, helping to reduce greenhouse gas emissions and combat climate change. Cameco's strategic initiatives, such as its partnership with Net Zero Nuclear, aim to expand global nuclear capacity and support the transition to a low-carbon economy. We believe we have the right strategy to achieve our vision, and we will do so in a manner that reflects our values. For more than 35 years, we have been committed to operating and delivering our products responsibly and profitably. We integrate sustainability principles and practices into every aspect of our business, from our corporate objectives and approach to compensation to our overall corporate strategy, risk management, and day-to-day operations, and they align with our values. We seek to be transparent with our stakeholders, keeping them updated on the risks and opportunities that we believe may have a significant impact on our ability to achieve our strategic plan and add long-term value. We recognize the importance of integrating certain sustainability factors, such as safety performance, a clean environment and supportive communities, into our executive compensation strategy as we see success in these areas as critical to the long-term success of the company.You can read more about our strategy in our 2024 annual MD&A and our approach to sustainability in our 2024 Sustainability Report.UraniumUranium production is central to our strategy, as it is the biggest value driver of the nuclear fuel cycle and our business. We have tier-one assets that are licensed, permitted, long-lived, and are proven reliable with capacity to expand. These tier-one assets are backed up by idle tier-two assets and what we think is the best exploration portfolio of mineral reserves and resources that in some cases can leverage our existing infrastructure. Currently, we believe that we have ample productive capacity with the ability to expand as the demand for nuclear energy and nuclear fuel grows.We are focused on protecting and extending the value of our contract portfolio, on aligning our production decisions with our contract portfolio and market opportunities thereby optimizing the value of our lowest cost assets. We also prioritize maintaining a strong balance sheet, and on efficiently managing the company. We have undertaken a number of deliberate and disciplined actions, including a focus on operational effectiveness to allow us to operate our assets more efficiently and with more flexibility. Learn moreFuel servicesOur fuel services segment supports our strategy to capture full-cycle value by providing our customers with access to refining and conversion services for both heavy-water and light-water reactors, and CANDU fuel and reactor component manufacturing for heavy-water reactors.As in our uranium segment, we are focused on securing new long-term contracts and on aligning our production decisions with our contract portfolio that will allow us to continue to profitably produce and consistently support the long-term needs of our customers.In addition, we are pursuing non-traditional markets for our UO2 and fuel fabrication business and have been actively securing new contracts for reactor components to support refurbishment of Canadian reactors.Learn moreWestinghouseIn 2023, we completed the acquisition of Westinghouse, a global provider of mission‐critical and specialized technologies, products and services for light-water reactors across most phases of the nuclear power sector, in a strategic partnership with Brookfield. We own a 49% interest in Westinghouse.We are enhancing our ability to compete for more business by investing in additional nuclear fuel cycle assets that we expect will augment the core of our business and offer more solutions to our customers across the nuclear fuel cycle. Like Cameco, Westinghouse has nuclear assets that are strategic, proven, licensed and permitted, and that are in geopolitically attractive jurisdictions. We expect these assets, like ours, will participate in the growing demand profile for nuclear energy.Learn moreGlobal Laser EnrichmentWe are interested in the second largest value driver of the fuel cycle, enrichment, and have a 49% interest in Global Laser Enrichment LLC (GLE). GLE is the exclusive licensee of the proprietary SILEX laser enrichment technology, a third-generation uranium enrichment technology. We are the commercial lead for the GLE project with a 49% interest and starting in 2023, an option to attain a majority interest of up to 75% ownership.Learn moreWe continually evaluate investment opportunities within the nuclear fuel value chain that align well with our commitment to add long-term value by managing our business responsibly and sustainably, and allow us to contribute to energy security solutions. Expanding our participation in the fuel cycle is expected to complement our tier-one uranium and fuel services assets, creating new revenue opportunities, and it enhances our ability to meet the increasing needs of existing and new customers for secure, reliable nuclear fuel supplies, services and technologies. 

On January 18, 2023, the Canadian Nuclear Safety Commission (CNSC) announced that Cameco Fuel Manufacturing (CFM) has been granted a 20-year renewal of its Fuel Facility Operating Licence.The renewed licence allows CFM to operate until February 28, 2043, at which time CFM can request to renew the licence for another period. As part of this licence, CFM will participate in a comprehensive mid-point (10-year) review of its operational performance. This requirement is in addition to the regulatory oversight report meeting and compliance verification activities carried out annually.Safety is at the core of Cameco’s operations and activities, and throughout this renewed licence period we remain committed to the protection of people and the environment.For more information please contact:Sara ForseyManager, Public & Government Affairssara_forsey@cameco.com289.771.1007Why Request a 20-year Term?Over the last 15-20 years, the CNSC strengthened its regulatory framework, with clarity provided in CNSC regulatory documents (REGDOCs) and Canadian Standards Association (CSA) nuclear standards. As well, the CNSC has introduced annual oversight reviews for all of the facilities regulated by the CNSC. These enhancements along with strong performance, have led to increased licence terms of 10 or more years because there are mechanisms in place to ensure that facility operations remain safe and that there are opportunities for the Commission to review performance in a public proceeding.CFM has consistently received satisfactory rankings from the CNSC while meeting all CNSC and other regulatory obligations. CFM’s consistent performance during the current licence period demonstrates our commitment to safety and the protection of people and the environment.What is the Production Limit Change?Currently, CFM’s licence has a monthly production limit which is 125 megagrams (1 megagram = 1 tonne) uranium dioxide (UO2) as pellets during any calendar month. We are requesting a slightly revised licence limit of an annual amount of 1,650 tonnes of uranium as UO2.In order to establish a consistent unit of measure for our production limits at all of our Ontario facilities, we are requesting an annual production limit in tonnes of uranium as UO2 instead of in megagrams. Accounting for the change in unit of measurement, the requested production limit represents an increase of approximately 24%.We are requesting this increase so that our licence limit mirrors the actual production capacity of our facility and the change from the monthly limit to an annual limit ensures that we can flex our operations as needed to meet business demands. What this translates to is a greater security of supply by ensuring we can increase production should there be a disruption in operations for any reason at any time. It will also ensure that we are able to take on new business opportunities when they arise.Application:Cameco Fuel Manufacturing - Licence Renewal - Letter (PDF 2MB) 

Nuclear energy is gaining momentum worldwide with its reliability, scalability, and carbon-free attributes. That strength is reflected in Cameco’s improving performance as we navigate challenges and seize opportunities.- Tim Gitzel, Chief Executive Officer

Measured and Indicated As of December 31, 2024(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 Lake75.54.888.1141.34.9515.423.612.9Kintyre   3,897.70.6253.553.553.5McArthur River71.82.283.660.32.313.16.74.7Millenium   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 Butte1,558.10.196.6939.30.357.313.913.9Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.15,530.30.078.49.49.4Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,885.6–183.4111,550.5–323.6507.0408.2Note 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 roundingInferredAs of December 31, 2024(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 River36.42.952.41.7Millenium412.43.1929.020.2Rabbit Lake2,460.90.6233.733.7Tamarack45.61.021.00.6Crow Butte531.40.161.81.8Gas Hills-Peach3,307.50.086.06.0Inkai33,742.20.0322.38.9North Butte-Brown Ranch294.50.070.40.4Ruby Ranch56.20.140.20.2Shirley Basin508.00.101.11.1Smith Ranch-Highland6,861.00.057.77.7Total49,323.5–199.8152.6Note 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, 2024.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, environmental, social and governmental 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 reservesWe 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 Cameco has an interest but is 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 485 million pounds U3O8 at the end of 2023, to 457 million pounds at the end of 2024. The change was primarily the result of:production at Cigar Lake, Inkai and McArthur River, which removed 27 million pounds of proven and probable reserves from our mineral inventory.The remaining changes are attributable to 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 409 million pounds U3O8 at the end of 2023 to 408 million pounds at the end of 2024. Our share of inferred mineral resources remained unchanged at 153 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, Cameco​Biman 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 2024 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 Q3 UpdateRabbit Lake remains in a safe state of care and maintenance following the suspension of production in 2016. We continue to evaluate opportunities to minimize care and maintenance costs while maintaining critical infrastructure and processes. We expect care and maintenance costs to range between $41 million and $45 million for 2025.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