Exhibit 99.1 Table of Contents 25 August 2025 APPENDIX 4D HALF YEAR ENDED 30 JUNE 2025 ST. HELIER, Jersey - (BUSINESS WIRE) – MAC Copper Limited (NYSE: MTAL; ASX:MAC) The Directors of MAC Copper Limited ARBN 671 963 198 (NYSE: MTAL; ASX: MAC), a private limited company incorporated under the laws of Jersey, Channel Islands ("MAC" or the "Company") are pleased to provide the Appendix 4D and the Half Year Report, for the half year ended 30 June 2025. The Appendix 4D and the Half Year Report, comprising this p ...