• Union #2 representing 50% of Mantoverde employees to take strike action
• Capstone to continue operations at up to 30% of normal production during strike
• Capstone remains committed to reaching a resolution through constructive dialogue

Capstone Copper Corp. announced that Union #2, one of the four unions at the Mantoverde Mine in Chile, representing approximately 50% of Mantoverde employees or 22% of the total workforce, will take strike action effective January 2, 2026. Prior to the strike notice, Capstone attempted, in good faith, to reach an agreement for a new collective bargaining agreement with Union #2. As a result of the strike, certain activities at the mine will be gradually reduced in a safe manner. During the strike, Capstone expects to continue operations at Mantoverde at a level of up to 30% of normal production. Capstone Copper remains willing to participate in meetings to reach a resolution, and will continue to adhere to legal procedures, respecting the rights of all its employees, inviting the union to engage in a constructive dialogue, and providing the authorities with all requested information. Capstone Copper is committed to the highest standards for integrity and transparency and looks forward to returning its focus to safe and responsible mining at Mantoverde, which brings great benefits to the workforce and surrounding communities. During 2025, Mantoverde was able to successfully negotiate new three-year collective bargaining agreements with the three other unions. In 2024, Capstone Copper distributed $682 million in economic value to Chile across its operations, including $136 million in employee wages and benefits. Today, Mantoverde employs approximately 1,270 total employees, including approximately 550 individuals from the local communities in the Atacama region of Chile. The total workforce at Mantoverde is approximately 2,940 individuals, including approximately 1,670 contractors.