Cameco Increases Ownership Stake in Cigar Lake Mine

Press Release

June 1, 2026

Cameco (TSX: CCO; NYSE: CCJ) and Orano Canada Inc. (Orano) have reached agreement with TEPCO Resources Inc. (TEPCO) to acquire TEPCO’s 5% participating interest in the Cigar Lake Joint Venture. Upon closing, Cameco’s ownership stake in the Cigar Lake uranium mine in northern Saskatchewan will increase by 2.871 percentage points to 57.418%, while Orano’s share will rise by 2.129 percentage points to 42.582%.

“Cigar Lake is among the world’s best uranium mines, producing the highest-grade uranium ore from a safe, reliable, and cost-effective operation,” said Cameco’s Chief Executive Officer Tim Gitzel. “Increasing our ownership in this world-class, tier-one asset further demonstrates our commitment to our strategy, with scarce, licensed, permitted assets like Cigar Lake playing an essential role in fueling global ambitions to expand nuclear energy generation. Cigar Lake’s success wouldn’t be possible without supportive neighbouring Indigenous communities, which provide vital workforce and supply chain support through our mutually beneficial partnerships.”

Cameco’s purchase cost to acquire our respective share of TEPCO’s interest in Cigar Lake is approximately $115.75 million, subject to customary closing adjustments. The acquisition is subject to certain regulatory approvals and other standard closing conditions. The transaction is expected to close in the third quarter of 2026.

Cigar Lake’s reserve and resource base includes proven and probable reserves estimated at 172.4 million pounds of U3O8, measured and indicated resources of approximately 26.3 million pounds, and inferred resources of 20.0 million pounds (100% basis, as of December 31, 2025). Since the time it began production in 2014, Cigar Lake has produced approximately 174.5 million packaged pounds (100% basis, as of December 31, 2025).

Our 2026 production outlook for the Cigar Lake mine is between 17.5 million and 18 million pounds of uranium concentrate (U3O8) on a 100% basis. In 2026, we plan to continue production and development activities in the area currently being mined (CLMain), while continuing to advance the development work related to Cigar Lake extension (CLExt) that is required to extend the life of the mine to 2036. Planned capital projects related to CLExt include construction of a freeze pad, freeze distribution, and underground infrastructure, with capital investments at Cigar Lake remaining consistent and aligned with our disciplined contracting, operational and capital allocation strategy.

Cigar Lake proven and probable mineral reserves

As of December 31, 2025 (100% basis); tonnes in thousands; pounds in millions)

		Proven			Probable			Total Mineral Reserves
Property	Mining Method	Tonnes	Grade (% U₃O₈)	Content (lbs. U₃O₈)	Tonnes	Grade (% U₃O₈)	Content (lbs. U₃O₈)	Tonnes	Grade (% U₃O₈)	Content (lbs. U₃O₈)	Metallurgical Recovery (%)
Cigar Lake	UG	263.7	17.06	99.2	215.3	15.43	73.2	479.0	16.33	172.4	98.9

Cigar Lake measured, indicated and inferred resources

As of December 31, 2025 (100% basis); tonnes in thousands; pounds in millions)

	Measured Resources (M)			Indicated Resources (I)			Total M+I	Inferred
Property	Tonnes	Grade (% U₃O₈)	Content (lbs. U₃O₈)	Tonnes	Grade (% U₃O₈)	Content (lbs. U₃O₈)	Content (lb U₃O₈)	Tonnes	Grade (% U₃O₈)	Content (lbs. U₃O₈)
Cigar Lake	82.3	5.00	9.1	153.8	5.07	17.2	26.3	163.4	5.55	20.0

Please see pages 97 and 98 of Cameco’s 2025 annual information form for the key assumptions, parameters and methods used to estimate the Cigar Lake mineral reserves and resources.

Qualified Persons

The technical and scientific information discussed in this document for Cigar Lake was approved by the following individuals who are qualified persons for the purposes of NI 43-101: