Our Annual Reports on Sustainability have been independently verified since 2005. External assurance of our 2020 reporting was conducted by Corporate Integrity Ltd. in accordance with the ICMM Mining Principles Assurance and Validation Procedure and the Copper Mark Assurance Process. Since 2009, site-level external assurance has been completed multiple times at all active mining and metals processing operations. For the majority of our operations, we conduct site-level external assurance via this program at least once every three years and annually at PT-FI and Cerro Verde. Due to COVID-19 travel restrictions, on-site assessments could not be conducted in 2020. However, virtual assurance was carried out in accordance with industry leading practices using a combination of video and online document sharing platforms and included ICMM and Copper Mark requirements (for copper producing sites). Moving forward, we have established a rolling assurance schedule to be conducted throughout the year, enabling more flexibility and adaptability to changing needs and circumstances. This schedule also supports the publication of our Annual Report on Sustainability earlier in the year. We will restart in-person assurance when COVID-19 safety conditions allow.

Note: Comprehensive Virtual Reviews entail exhaustive analyses of evidence examples and in-depth virtual meetings with site-based and corporate-level subject matter experts. Desktop Reviews entail exhaustive analyses of evidence examples and select interviews with site-based and corporate-level subject matter experts, when clarifications are necessary.