Mr. Cashel Meagher reports

CAPSTONE COPPER PUBLISHES 2025 SUSTAINABILITY REPORT

Capstone Copper Corp. has published its 2025 sustainability report. The report has been prepared in accordance with the Global Reporting Initiative (GRI) standards, Sector Standard GRI 14: Mining Sector 2024, and the SASB Metals & Mining Sustainability Accounting Standard. The report details the company's performance on material sustainability topics across its operations for the period from Jan. 1, 2025, to Dec. 31, 2025.

Cashel Meagher, president and chief executive officer of Capstone, commented: "I am pleased to share Capstone Copper's 2025 sustainability report, which reflects how we continued to embed our sustainable development strategy throughout our business. Two thousand twenty-five was a year of meaningful progress made possible by our team and guided by our commitment to being prudent in thought and reliable in action. We continued to build a culture grounded in safety, accountability and disciplined execution, all while delivering production growth to meet the increasing demand for copper, the key metal for electrification. Looking towards the future, sustainability remains inseparable from our business strategy as we aim to create lasting value for shareholders while contributing positively to our people, the environment and our operating communities."

2025 sustainability report highlights

Throughout 2025, the company advanced its sustainable development strategy across its five priority areas: climate, water, tailings, biodiversity and communities. Capstone worked collaboratively across the company to achieve sustainability milestones on multiple fronts, highlighted below:

• Improved health and safety performance through Capstone's health, safety and environment (HSE) road map: Two thousand twenty-five marked the first year of our three-year CuSafe HSE road map. Improved leadership training, system implementation and standardized processes resulted in meaningful progress on safety metrics, including an approximately 22-per-cent reduction in recordable injuries year over year.
• Full participation in the Copper Mark assurance process across all sites: Pinto Valley received the Copper Mark award in 2025, joining Mantos Blancos and Mantoverde, which received the award in 2023, and started the second cycle of the assurance process in 2025. Cozamin also commenced the assurance process in 2025, extending Capstone Copper's commitment to responsible copper production across all sites.
• Launched Capstone-wide biodiversity and social performance standards: Capstone achieved two of its sustainable development strategy targets by setting minimum performance standards connected to biodiversity and social performance in 2025, with all sites completing self-assessments and initiating action plans to strengthen impact management and compliance.
• Advanced water stewardship practices through a water management standard: Capstone strengthened governance over freshwater use, recycled water and climate-related water risks, with all sites completing ICMM-aligned water stewardship conformance assessments and site-wide water balances.
• Strengthened climate governance and risk assessment: Capstone advanced its climate-related risk assessment, expanded Scope 3 data collection, and strengthened internal controls over GHG (greenhouse gas) emissions reporting to support decision making and disclosure.
• Increased transparency and data systems maturity: Among other initiatives, Capstone launched an interactive tailings storage facility platform and published updated tailings management disclosures to support decision making, transparency and future disclosure.

Some 2025 data trends include:

• Total energy use increased by 14 per cent in 2025 compared with 2024, primarily due to higher energy consumption driven by a higher proportion of copper concentrate production compared with copper cathode production. Renewable energy as a percentage of total energy improved to 24 per cent in 2025 versus 21 per cent in 2024, primarily attributable to purchasing all electricity for Mantoverde and Mantos Blancos from I-REC certified renewable sources in 2025;
• Achieved a 7-per-cent reduction in market-based GHG emissions from fuel and power (compared with Capstone's recalculated 2021 baseline) in pursuit of the company's target for a 30-per-cent reduction by 2030. Market-based GHG emissions intensity declined by 13 per cent year over year per tonne of copper produced due to increased production relative to energy use at Mantoverde and Mantos Blancos as both mines reached their name-plate capacities;
• The proportion of low-quality water withdrawals as a portion of total water withdrawals increased 6 per cent to 87 per cent, compared with Capstone's 2021 baseline of 81 per cent. Freshwater use intensity per tonne of ore processed increased by 30 per cent in 2025 (compared with Capstone's 2021 baseline), reflecting higher water demand associated with changes in ore mineralogy and processing methods, with a greater share of sulphide processing driving higher water intensity;
• Achieved 80-per-cent conformance with the Global Industry Standard for Tailings Management (GISTM) companywide, up from 48 per cent in 2024, in pursuit of our commitment to implement the GISTM across all tailings storage facilities by 2028;
• Per 200,000 hours in 2025, Capstone's combined work force lost-time injury frequency rate (LTIFR) significantly improved to 0.23 compared with 0.48 in 2024 and the company's total reportable injury frequency rate (TRIFR) improved to 0.69 compared with 0.91 in 2024. Two thousand twenty-five marked the first year of consistent leading indicators across all operations, including greater-than-90-per-cent completion of programmed HSE training, greater-than-75-per-cent visible felt leadership program achievement and greater than 90 per cent of HSE actions completed by the agreed target date;
• Capstone's combined work force increased by 20 per cent in 2025 to 8,152 (versus 6,806 in 2024), primarily reflecting growth at Capstone's Chilean operations, including the initiation of the first stages of project-related work at Santo Domingo. The proportion of women employees increased to 12 per cent in 2025 from 10 per cent in 2024, reflecting Capstone's continued focus on diversity and inclusion efforts. Global employee turnover rate decreased to 12 per cent in 2025, compared with 15 per cent in 2024, indicating a more stable employment base.

The 2025 sustainability report is available on Capstone's website.

About Capstone Copper Corp.

Capstone is an Americas-focused copper mining company headquartered in Vancouver, Canada. Capstone's operating portfolio of assets includes the Pinto Valley copper mine located in Arizona, U.S. the Cozamin copper-silver mine located in Zacatecas, Mexico, the Mantos Blancos copper-silver mine located in the Antofagasta region, Chile, and the Mantoverde copper-gold mine, located in the Atacama region, Chile. Capstone's growth pipeline includes the fully permitted Santo Domingo copper-iron-gold project, located approximately 35 kilometres northeast of Mantoverde in the Atacama region, Chile, as well as a portfolio of exploration properties in the Americas.

Capstone's strategy is to unlock transformational copper production growth while executing on cost and operational improvements through innovation, optimization, and safe and responsible production throughout the company's portfolio of assets. Capstone focuses on profitability and disciplined capital allocation to surface stakeholder value. The company is committed to creating a positive impact in the lives of its people and local communities, while delivering compelling returns to investors by responsibly producing copper to meet the world's growing needs.

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