APPENDIX 4E PRELIMINARY FINAL RESULT

Notice to ASX 2 March 2026

The Board of Bougainville Copper Limited (ASX: BOC) announces the following preliminary results of the company for the year ended 31 December 2025, together with comparable results for the 12 months to 31 December 2024, including an update of significant events.

Results
The directors of Bougainville Copper Limited (BCL) announce the following Preliminary final results of the company for the year ended 31 December 2025 together with comparable results for twelve months to 31 December 2024.

The Bougainville Copper Foundation Limited (BCF) is a fully owned subsidiary of BCL. The balance sheet of BCF is consolidated with BCL as of 31 December 2025 and comparatives for the previous year.

For the year ended 31 December 2025, the Group recorded a loss of K16 million compared to a loss of K13.4 million in the previous year. Realised gains on sales of investments are not recorded in the income statement but are reported by a transfer directly to retained earnings in Shareholders funds. The fair value of investments increased by K0.7 million, compared to a decrease of K2.3 million the previous year. Income from interest and dividends was similar to the previous year totalling K3.5 million compared to K3.4 million in the previous year.

During 2025, expenditure was again focused on meeting EL01 commitments and obligations as set out in the license approval conditions and workplan requirements. These included ongoing landowner identification studies and Exploration Licence Land Access and Compensation Agreement with landowners, stakeholder engagements, delivery of small community support projects. The process of identifying a development partner progressed

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