Exhibit 99.1

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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 page and the following 19 pages, constitutes the half year end financial information given to the ASX under Listing Rule 4.2A and should be read in conjunction with the Financial Report for the year ended 31 December 2024.

The Appendix 4D and Half Year Report have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (IASB), with a reconciliation of any non-IFRS measure. The functional currency of the majority of the Company’s operations is United States dollars and, unless otherwise defined in this report, $, USD and US$ amounts are in United States dollars and A$ are in Australian dollars.

Current reporting period: 6 months ended 30 June 2025 (HY25)

Previous corresponding reporting period: 6 months ended 30 June 2024 (HY24)

Results for the announcement to the market

¹ See “Non-IFRS financial information” and refer to table 2 for the reconciliation of Underlying EBITDA

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Distributions

There were no dividends paid to shareholders during this reporting period (HY24: Nil). There is no final dividend declared or proposed for the half year ended 30 June 2025 (HY24: Nil).

Net tangible assets

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Contacts

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This announcement is authorised for release by the Board of Directors.

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JUNE 2025 HALF YEAR FINANCIAL RESULTS

RECORD DAILY PRODUCTION², RECORD QUATERLY C1 COSTS AND OPERATING FCF

HIGHLIGHTS

During the half year ended 30 June 2025, we delivered record production and earnings generation while making strong progress towards our strategic goals.

Material improvement in safety performance

Record daily copper production with improved grade

Refinance leads to increased liquidity, flexibility and balance sheet strength

Glencore contingent consideration

² Record production referencing the record daily production in June 2025 of the CSA Copper Mine under MAC ownership

³ Refer to ASX and NYSE release ‘June 2025 Quarterly Report’ dated 24 July 2025

⁴ See “Non-IFRS financial information” and refer to table 5 for the reconciliation of C1 cash cost

⁵ Converted at USD:AUD exchange rate of 0.655 as at 30 June 2025

⁶ Comparing the previous weighted average interest cost of ~9.72% to the new all-in interest rate of ~6.85% - the new interest rate is linked to SOFR and a leverage margin grid

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Targeting copper production of >50ktpa by 2026

Summary of financial results

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MAC Copper Limited’s CEO, Mick McMullen, said:

“Our team has built on the positive momentum achieved on safety with a further reduction in not only the total incidents recorded, but also the severity of these incidents during the half year with TRIFR reducing to 6.9, down from 10.9 recorded at the end of 2024. This is a remarkable effort considering the disruptive impact the Harmony Transaction had on site in the lead up to and immediately after announcement and I want to thank all of our people for continuing to focus on the job at hand throughout this period.

As noted in previous announcements, copper production is driven by a small number of large-tonnage, high-grade stopes and the timing of when these are sequenced in the year. Mining these higher-grade stopes in the second quarter resulted in the operations again performing at record levels under MAC’s ownership, including a record-breaking 385 tonnes of copper produced in one day, and we ended the half year with a total production of 19,231 tonnes at an average grade of 4.3% Cu.

Our C1 for HY25 decreased by circa 19% compared to HY24, with the C1 for the month of June 2025 also setting a new record low of US$0.94/lb under MAC ownership with around 5,556 tonnes of copper being produced in the month, at a grade of 6.2%, again showcasing the low-cost nature of the CSA Copper mine.

We made great progress on delivering on our growth strategy, supported by our two key growth projects which include the expansion of the mine to include the new Merrin Mine and bringing the Capital Vent project online by Q4 2025 and Q3 2026 respectively. We completed 1,891 metres of underground development during HY25, with 1,196 for the second quarter, another record under MAC ownership.

We further strengthened our balance sheet on the back of the successful amendment to our debt facilities We ended HY25 with circa US$102 million in cash.

⁷ See “Non-IFRS financial information” and refer to table 2 for the reconciliation of Underlying EBITDA

⁸ See “Non-IFRS financial information” and refer to table 5 for the reconciliation of C1 cash cost

⁹ See “Non-IFRS financial information” and refer to table 6 for the reconciliation of Total cash cost

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We progressed the Harmony Transaction with the announcement of the completion of key conditions precedent recently as announced with further updates to come. The Transaction presents a great outcome for all stakeholders in the CSA Copper Mine, who will benefit from the stewardship of a well-respected and high-quality operator in Harmony. Alongside my fellow directors, I have no hesitation in supporting the Transaction, in the absence of a superior proposal. ”

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IMPORTANT INFORMATION AND DISCLAIMER

Estimates of Mineral Resources and Ore Reserves and Production Target

This release contains estimates of Ore Reserves and Mineral Resources as well as a Production Target. The Ore Reserves, Mineral Resources and Production Target are reported in MAC’s ASX Announcement dated 24 February 2025 titled ‘2024 Resource and Reserve Statement and Production Guidance’ (the R&R Announcement). The Company is not aware of any new information or data that materially affects the information included in the R&R Announcement, and that all material assumptions and technical parameters underpinning the estimates or Ore Reserves and Mineral Resources in the R&R Announcement continue to apply and have not materially changed. The material assumptions underpinning the Production Target in the R&R Announcement continue to apply and have not materially changed. It is a requirement of the ASX Listing Rules that the reporting of ore reserves and mineral resources in Australia comply with the JORC Code. Investors outside Australia should note that while exploration results, mineral resources and ore reserves estimates of MAC in this presentation comply with the JORC Code, they may not comply with the relevant guidelines in other countries and, in particular, do not comply with (i) National Instrument 43-101 (Standards of Disclosure for Mineral Projects) of the Canadian Securities Administrators; or (ii) the requirements adopted by the Securities and Exchange Commission (SEC) in its Subpart 1300 of Regulation S-K. Information contained in this presentation describing mineral deposits may not be comparable to similar information made public by companies subject to the reporting and disclosure requirements of Canadian or US securities laws.

Forward Looking Statements

This release includes “forward-looking statements.” The forward-looking information is based on the Company’s expectations, estimates, projections and opinions of management made in light of its experience and its perception of trends, current conditions and expected developments, as well as other factors that management of the Company believes to be relevant and reasonable in the circumstances at the date that such statements are made, but which may prove to be incorrect. Assumptions have been made by the Company regarding, among other things: the price of copper, continuing commercial production at the CSA Copper Mine without any major disruption, the receipt of required governmental approvals, the accuracy of capital and operating cost estimates, the ability of the Company to operate in a safe, efficient and effective manner and the ability of the Company to obtain financing as and when required and on reasonable terms. Readers are cautioned that the foregoing list is not exhaustive of all factors and assumptions which may have been used by the Company. Although management believes that the assumptions made by the Company and the expectations represented by such information are reasonable, there can be no assurance that the forward-looking information will prove to be accurate.

MAC’s actual results may differ from expectations, estimates, and projections and, consequently, you should not rely on these forward-looking statements as predictions of future events. Words such as “expect,” “estimate,” “project,” “budget,” “forecast,” “anticipate,” “intend,” “plan,” “may,” “will,” “could,” “should,” “believes,” “predicts,” “potential,” “continue,” and similar expressions (or the negative versions of such words or expressions) are intended to identify such forward- looking statements. These forward-looking statements include, without limitation, MAC’s expectations with respect to future performance of the CSA Copper Mine. These forward-looking statements involve significant risks and uncertainties that could cause the actual results to differ materially from those discussed in the forward-looking statements. Most of these factors are outside MAC’s control and are difficult to predict. Factors that may cause such differences include, but are not limited to: the supply and demand for copper; the future price of copper; the timing and amount of estimated future production, costs of production, capital expenditures and requirements for additional capital; cash flow provided by operating activities; unanticipated reclamation expenses; claims and limitations on insurance coverage; the uncertainty in Mineral Resource estimates; the uncertainty in geological, metallurgical and geotechnical studies and opinions; infrastructure risks; and other risks and uncertainties indicated from time to time in MAC’s other filings with the SEC and the ASX. MAC cautions that the foregoing list of factors is not exclusive. MAC cautions readers not to place undue reliance upon any forward-looking statements, which speak only as of the date made. MAC does not undertake or accept any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements to reflect any change in its expectations or any change in events, conditions, or circumstances on which any such statement is based.

More information on potential factors that could affect MAC’s or CSA Copper Mine’s financial results is included from time to time in MAC’s public reports filed with the SEC and the ASX. If any of these risks materialize or MAC’s assumptions prove incorrect, actual results could differ materially from the results implied by these forward-looking statements. There may be additional risks that MAC does not presently know, or that MAC currently believes are immaterial, that could also cause actual results to differ from those contained in the forward-looking statements. In addition, forward-looking statements reflect MAC’s expectations, plans or forecasts of future events and views as of the date of this communication. MAC anticipates that subsequent events and developments will cause its assessments to change. However, while MAC may elect to update these forward-looking statements at some point in the future, MAC specifically disclaims any obligation to do so, except as required by law. These forward-looking statements should not be relied upon as representing MAC’s assessment as of any date subsequent to the date of this communication. Accordingly, undue reliance should not be placed upon the forward-looking statements.

Non-IFRS financial information

MAC’s results are reported under International Financial Reporting Standards (IFRS), noting the results in this report have not been audited or reviewed. This release may also include certain non-IFRS measures including C1, Total Cash costs, Free Cash Flow and Underlying EBITDA. These C1, Total Cash cost, Free Cash Flow and Underlying EBITDA measures are used internally by management to assess the performance of our business, make decisions on the allocation of our resources and assess operational management. Non-IFRS measures have not been subject to audit or review and should not be considered as an indication of or alternative to an IFRS measure of financial performance.

C1 Cash Cost

C1 costs are defined as the costs incurred to produce copper at an operational level. This includes costs incurred in mining, processing and general and administration as well freight and realisation and selling costs. By-product revenue is credited against these costs to calculate a dollar per pound metric. This metric is used as a of measure operational efficiency to illustrate the cost of production per pound of copper produced.

Total Cash Cost

Total cash costs include C1 cash costs plus royalties and sustaining capital less inventory WIP movements. This metric is used as a measure of operational efficiency to further illustrate the cost of production per pound of copper produced whilst incurring government-based royalties and capital to sustain operations.

Free Cash Flow

Free cash flow is defined as net cash provided by operating activities less sustaining capital spend on additions to property, plant, equipment and mineral interests. This measure, which is used internally to evaluate our underlying cash generation performance and the ability to repay creditors and return cash to shareholders, provides investors with the ability to evaluate our underlying performance.

Underlying EBITDA

Underlying EBITDA is profit before net finance costs, tax, depreciation and amortisation and after any earnings adjustment items, impacting profit. We believe that Underlying EBITDA provides useful information, but should not be considered as an indication of, or alternative to, profit or attributable profit as an indicator of operating performance.

Copper grade

Unless stated otherwise, copper grade mentioned throughout this document refers to mined ore grade.

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FINANCIAL AND OPERATIONAL REVIEW

The Half Year Report reflects the consolidated results of MAC and its subsidiaries (collectively referred to as the MAC, MAC Group or the Group). The financial results of the MAC Group for the half year ended 30 June 2025 were largely driven by the operation of its core asset being its 100% owned CSA Copper Mine. The CSA Copper Mine is an established, high grade, producing, underground copper mine, with estimated ore reserves supporting approximately ten years of operation as at 30 June 2025.

Financial performance summary

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Income statement analysis

Revenue

Copper production is driven by a small number of large-tonnage, high-grade stopes and the timing of when these are sequenced in the period.

During the first quarter, copper production had decreased to 8,644 tonnes at ~4.1% Cu with a higher-grade stope only accessed in the latter part of March 2025. Mining these higher-grade stopes in the second quarter not only resulted in the operations returning to normal but also achieving record levels under MAC’s ownership, including a record-breaking ~385 tonnes of copper produced in one day and increase in second quarter copper production to 10,587 tonnes at ~4.4% Cu.

The sequential increase in copper production in the second quarter resulted in the HY25 copper production decreasing by ~2% compared to HY24. However, the increased June 2025 production and lack of flexibility in the shipping schedule led to a 16% decrease in copper sold for HY25 compared to HY24.

¹⁰ See “Non-IFRS financial information” and refer to table 2 for the reconciliation of Underlying EBITDA

¹¹ See “Non-IFRS financial information” and refer to table 3 for the reconciliation of free cash flow

¹² See “Non-IFRS financial information” and refer to table 5 for the reconciliation of C1 cash cost

¹³ See “Non-IFRS financial information” and refer to table 6 for the reconciliation of Total cash cost

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Strong copper prices during HY25 and a reduction of ~73% in TCRC¹⁴ offset some of the reduction in copper sold with total revenue decreasing by 11% when compared to HY24, as summarised in the following table:

Table 1: Revenue break-down

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Earnings analysis

MAC Group’s HY25 statutory loss after tax of ~US$77 million, is primarily due to the net financing costs on loans and borrowings of ~US$52 million and other non-cash movements of ~US$57 million in fair value of financial instruments. In HY24, these costs were ~US$33 million and ~US$109 million, respectively.

The ~63% increase in HY25 net finance costs on loans and borrowings predominantly relates to the unwinding of the discount on the Mezzanine Facility including additional costs incurred on the early repayment of this facility and the refinancing of the Senior Debt. The ~48% decrease in non-cash movements in fair value of financial instruments is mainly driven by the repayment of the Mezzanine Facility in the current period and a ~US$39 million revaluation of the public and private warrants immediately before redemption in the comparative period.

MAC’s HY25 Operating profit and Underlying EBITDA have decreased by ~35% and ~10% respectively, which was mainly driven by the decrease of ~16% in copper sold for HY25. Operating profit was also affected by the additional share-based payment expense recognised in HY25 which would be due when the Harmony Transaction becomes legally effective.

Table 2: Reconciliation of loss after tax to Underlying EBITDA

¹⁴ Refer to ASX and NYSE release ‘December 2024 Quarterly Report’ dated 29 January 2025

¹⁵ Related to the ASX IPO, acquisition of the CSA Copper Mine, refinancing and other investment decisions

¹⁶ Includes discretionary bonuses and share-based payments that would be due when the Harmony Transaction is approved

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Corporate and administration expenses

Excluding non-routine expenses such as the IPO and transaction costs and additional share-based payments due when the Harmony Transaction becomes legally effective, corporate and administration expenses during HY25 have decreased by ~US$0.5 million. This decrease reflects management’s continuous focus on cost efficiencies and is an outcome of the establishment of a permanent, qualified, skilled and experienced workforce.

Hedging

Prevailing copper prices during HY25 were higher than those locked in the commodity swap arrangement and lead to a realised hedging loss of ~US$8 million included within finance costs (HY24: US$6 million).

Balance sheet analysis

Cash and liquidity

At the end of HY25, MAC had a cash balance of ~US$102 million and pro-forma liquidity of ~US$196 million, after including ~US$59 million undrawn revolving facility, ~US$11 million outstanding Quotational Period receipts, ~US$18 million of unsold concentrate and ~US5.5 million strategic investment held in POL (31 December 2024: cash and cash equivalents of ~US$172 million and pro-forma liquidity of ~US$213 million).

Loans and borrowings

Net reduction in current and non-current loans and borrowings during the period was mainly driven by the ~US$160 million repayment of the Mezzanine Facility, including capitalised interest to June 2025 and 4% premium, ~US$11 million repayment of silver and copper stream loans, and the ~US$66 million draw down of revolving facility (HY24: US$45 million repayments of loans and borrowings).

Other assets and liabilities

During HY25, the Group incurred capital expenditure of ~US$14 million in relation to the development of the CSA Copper Mine (HY24: US$11 million) and acquired other equipment and assets totalling ~US$19 million to support the mining operations (HY24: US$18 million).

Derecognition of the embedded derivative related to the Mezzanine Facility reduced the derivative financial liabilities by ~US$34 million. However, rising copper prices adversely affected the fair valuation of derivative financial liabilities at the end of HY25 and resulted in a net decrease of ~US$3.5 million (HY24: ~US$20 million).

Based on the average daily London Metals Exchange closing price of copper for the 18-month period leading up to the end of June 2025, the condition of the first contingent payment of US$75 million to Glencore was satisfied on 20 August 2025. This trigger of the first contingent payment and the increase in copper price outlook impacted the fair valuation resulting in other financial liabilities increasing from ~US$142 million at 31 December 2024 to ~US$171 million at 30 June 2025.

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Cash flow statement analysis

Operating activities

MAC generated cash flows from operating activities of ~US$65 million in HY25 (~US$55 million in HY24). The cash flows from operating activities were mainly a result of ~US$170 million received from Glencore against sale of Copper (~US$194 million in HY24), offset by ~US$88 million paid to employees and suppliers (~US$110 million in HY24) and ~US$17 million of net interest payments (~US$29 million in HY24).

Investing activities

Investing activities in HY24 totalling ~US$38 million (HY24: ~US$129 million) primarily included ~US$14 million spent for the development of the CSA Copper Mine (HY24: ~US$11 million), ~US$19 million spent on other equipment and assets (HY24: ~US$13 million), ~US$3 million spent on exploration (HY24: ~US$3 million). HY24 investing activities also included consideration and transaction costs paid for the acquisition of the CSA Copper Mine amounting to ~US$98 million.

Financing activities

In HY25, repayments of Mezzanine Facility, and silver and copper stream loans totalling ~US$157 million offset by the ~US$66 million draw down of the revolving facility were the main cash flows related to financing activities. In HY24, ~US$212 million (~A$325 million at A$17.00 per CDI), before costs, raised as part of the ASX listing, was the main contributor of the net inflows from financing activities. These were offset by repayment of senior debt, Glencore working capital loan and silver and copper stream loans totalling ~US$57 million.

Table 3: Reconciliation of cash flows from operations to free cash flow

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Entities over which control has been gained or lost during the period

In HY25, the Company has not gained or lost control over any entity (HY24: None)

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Operational performance summary

ESG

Safety

The Total Recordable Injury Frequency Rate (TRIFR) for the CSA Copper Mine at the end of HY25 was 6.9 (HY24: 14.4). This is well below the NSW underground metalliferous TRIFR average of 9.8¹⁷.

The positive momentum that started towards the end of 2024 has been maintained, with both the total number of incidents recorded and the severity of these incidents further reducing during the half year.

Graph 1: 12 Months TRIFR Average: CSA vs Industry

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Sustainability Report

MAC recognizes the importance of our environmental, social and governance responsibilities and that sustainability strategies more broadly are integral to the way we operate and essential to the accomplishment of our goals.

As a result, in HY25, we published our inaugural annual sustainability report on 28 March 2025, which provides an overview of our material ESG topics, a summary of current performance and an outline of future activities and initiatives to improve our reporting and disclosures over time. Further, in preparation for the 2026 reporting in compliance with AASB S2, MAC undertook a Climate Risk Assessment to identify and quantify our climate related risks and opportunities. This risk assessment is the basis for the AASB S2 Climate related disclosures, which require mandatory reporting for MAC in 2026.

Community

MAC donated A$100,000 to the local Cobar Shire Council’s Museum’s Coach House and Underground Mining Experience project which has also been funded through two New South Wales Government programs. The aim of the project is to increase visitation, expenditure and extend the length of stay for visitors to regional New South Wales. In addition to the donation, MAC also contributed underground video footage taken at the CSA Mine which will be used in the museum’s underground experience. MAC believes it is important to invest in the local community in which it operates.

¹⁷ Industry TRIFR source: Mine Safety performance report 2023-2024, Resource regulator Department of Regional NSW

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Regulatory

The CSA Forward Plan has been updated and submitted to the NSW Resources Regulator along with a revised RCE. The revised RCE resulted in a reduction of ~A$4 million, which was mostly for works which have been completed on the current Southern Tailings Facility. A rehabilitation risk assessment was undertaken as part of the compliance requirements with the NSW Resources Regulator and to inform MAC of rehabilitation risks and requirements. There have been no reportable environmental incidents during the half year.

Construction activities on the Stage 10 embankment raise have been ongoing with works on the foundation and development on the East Mound. The majority of the West Mound has been raised to Stage 10. A key trench has been completed and backfilled on the northern half of the mound with a large portion of the northern half raised. The Stage 10 TSF embankment provides TSF capacity out to 2030 and is one of the three main capital projects being undertaken in 2025.

Production

Physicals

HY25 was initially affected by the sequencing of stopes mined in January and February 2025 with a higher-grade stope only accessed in the latter part of March 2025. This was then offset by a ramp up in production through mining the higher-grade stopes during the rest of the half year. Production also benefited from increased average milled copper grade of 4.29% for the half year. Refined mining methods implemented in 2024, including updated blasting techniques and double lift stope extraction sequence continued to result in less mining dilution with stronger grades and less total ore tonnes for the same metal during the half year.

Table 4: Production physicals

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C1 Cash Cost

C1 cash cost decreased by ~19% from US$2.08/lb in HY24 to US$1.67/lb in HY25 mainly attributable to an increase of ~13% in copper grade processed, a decrease of ~73% in TCRCs and an overall decrease in operating costs of ~13%.

Table 5: Reconciliation of cost of goods sold to C1 cash cost

Table 6: Reconciliation of total cash costs excluding capital spend to total cash cost

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Treasury

Cash position, liquidity and debt facilities

MACs cash holding at the end of HY25 was ~US$102 million (31 December 2024: ~US$172 million) and a net debt¹⁹ position of ~US$123 million (31 December 2024: ~US$132 million).

There was ~$28.6 million of cash received for copper concentrate sold to Glencore on 24 June 2025 for which revenue is to be accounted for in early July 2025.

The cash position also reflects ~US$160 million repayment of the Mezzanine Facility, including capitalised interest to June 2025 and 4% premium, ~US$11 million repayment of silver and copper stream loans, ~US$66 million draw down of revolving facility, ~US$4.2 million in interest payments for the Senior debt and US$14.3 million interest payments for the Mezzanine Facility during the half year.

At the end of HY25, MAC had a pro-forma liquidity of ~US$196 million, after including ~US$59 million undrawn revolving facility, ~US$11 million outstanding Quotational Period receipts, ~US$18 million of unsold concentrate and ~US5.5 million strategic investment held in POL (31 December 2024: Pro-forma liquidity of ~US$213 million).

Hedging

In adherence to our Debt Facility Agreement, MAC Copper previously implemented a hedging program covering the period to June 2026. During the year, the Company delivered 6,210 tonnes of copper into the hedge book at a price of US$3.72/lb. A summary of our open hedge positions as at 30 June 2025 is included below:

Table 7: Hedge position

¹⁸ Excluding ventilation project

¹⁹ Senior Debt + Mezzanine Facility - Cash and cash equivalents (excluding streams)

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Contingent consideration for the acquisition of CMPL

Under the terms of the CMPL Share Sale Agreement with Glencore, MAC will become obliged to pay to Glencore:

Based on the average daily London Metal Exchange closing price of copper, the first US$75 million liability was triggered subsequent to the period end on 20 August 2025.

Under the terms of the CMPL Share Sale Agreement and the Intercreditor Deed, any obligation on MAC to make the contingent payments to Glencore upon satisfaction of the applicable condition is deferred until the earlier of:

Given the terms of the CMPL Share Sale Agreement and Intercreditor Deed, MAC expects the first contingent payment to become payable by MAC on 17 June 2026, being one business day after the three-year anniversary of when MAC originally acquired the CSA Copper Mine.

Given MAC’s current liquidity position, the Company expects to be able to fully cash settle this obligation when it becomes payable.

Ongoing projects

Pathway to >50,000 tonne per annum of copper production

The CSA mine is already benefiting from productivity improvements initiated under MAC ownership such as double lift stopes, and operational efficiencies aimed at reducing waste and ensuring efficient delivery of ore.

To further progress towards becoming a 50ktpa+ copper equivalent producer in 2026 and beyond, there are two key projects that are essential to achieve this, being the Ventilation project which is due for completion Q3 2026 and the opening up of the new Merrin Mine with first ore expected in Q4 2025.

The delivery of both these are essential to achieve our strategic goal of uplifting production to over 50,000 tonnes of copper equivalent production by 2026 and unlock the full potential of the CSA copper mine.

Ventilation project

The Capital Vent Project is designed to support increased mining activity and improving distribution of chilled air to lower mine levels and ensuring operational longevity beyond the current reserve life. The project remains a key enabler for sustained production growth at CSA.

Total spend in HY25 was US$11 million, with 904 metres of development being completed. Progress continued establishing access to the first raise bore location, additional geotechnical drilling was completed, and procurement of ventilation fans advanced.

The Company has employed a dedicated Project Manager with extensive underground mine infrastructure experience to have overall control of the project with specific focus on managing the fan chamber excavation and fan installation. This work is a critical time and cost aspect of the project.

Four vendors have pre-qualified to Design, Engineer, Construct & Commission the fan chamber component of the project and tender documents are being finalised. In addition, raise boring contractor negotiations are being finalised.

The project is progressing well, with development successfully integrated into existing operations. It remains on target to be completed by Q3 2026.

The new Merrin Mine

Progress continued in developing the Merrin Mine in HY25 and a total of 740 metres of capital development was completed which demonstrated that development rates are materially faster (and cheaper) in the Merrin Mine than the existing mining areas with fewer operational constraints.

The new Merrin Mine presents an opportunity for incremental copper and zinc production at the CSA Mine, and is an additional mining area not currently connected to the bottom of the mine located ~150m below the surface. Drilling to upgrade this deposit from resource to reserve in some areas has been completed, with ore mining expected to commence by Q4 2025. Drilling continues in the upper remnant sections to provide grade and geotechnical data.

Total capital spend in HY25 was US$4.2 million, primarily allocated to project startup, equipment costs, decline development and diamond drilling.

Conceptual mine design for the first stage of the Merrin Mine has focused on the 2-level to 6-level which will allow for quicker and progressive access to the ore. Conceptual planning of the copper and zinc stopes and related development is completed which supports the commitment for further drilling to raise the resource category in these areas to measured and indicated.

An additional benefit of completing the Merrin Mine is the opportunity to replace the existing decline to allow access to significant volumes of sterilised ore. This will also provide the mine with a larger, more modern decline suited to larger equipment that will better service the entire mine.

In addition, POL has also recommissioned its Endeavour concentrator providing a processing pathway for the Merrin zinc ore. MAC has an existing toll treatment agreement with POL to treat the Merrin zinc ore at the Endeavour Mill which is 45km to the north of CSA via sealed roads.

Exploration

During HY25, MAC invested US$3m in exploration and evaluation activities, which primarily included continued exploratory and resource definition diamond drilling on CML5.

A Fixed Loop Electromagnetic (FLEM) survey, accompanied with low-temperature Superconducting Quantum Interference Devices (SQUIDs), was completed across the Bundella Project area, located 15 km north of the CSA Mine and 18 km east of the Endeavour Mine, on EL5693. The area shares a lithological and structural setting analogous to the CSA Mine and is considered highly prospective for hosting high-grade Cobar-style deposits.

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While modelling is ongoing, the survey has identified a significant late-time electromagnetic displaying key characteristics typical of a Cobar-style deposit, including:

MAC considers the E2C anomaly a high-priority target with all necessary approvals obtained during the half year. Diamond drilling commenced in early July 2025 to test the source of the conductor.

Mine Plan, Resource and Reserve

The update to the Reserves and Resources was announced on 25 February 2025 – see announcement for detail and summary of the changes made.²⁰

²⁰ Refer to ASX release ‘Updated Resource & Reserve Statement & Production Guidance’ dated 24 February 2025
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DIRECTORS’ REPORT

The directors present their report together with the consolidated financial statements of MAC Copper Limited (MAC or the Company) and its subsidiaries, Metals Acquisition Corp. (Australia) Pty Ltd (MAC AU) and Cobar Management Pty Ltd (CMPL) (together the Group) for the half year ended 30 June 2025 and the auditors’ review report thereon.

Directors

The directors of the Company at any time during or since the end of the financial period are:

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The directors held office for the entire period unless otherwise stated.

Principal activities

The principal activities of the Group during the course of the half year were the operation of the CSA Copper Mine in Australia for the mining and production of copper and silver.

The CSA Copper Mine is an established, high grade, producing, underground copper mine, with current estimated Ore Reserves supporting approximately ten and a half years of operation.

There were no other significant changes in the nature of the activities of the Group during the half year.

Review of the results and operations

The review of the results and operations of the Group is set out on pages 7 to 16, and forms part of the Directors’ Report.

Dividends

No dividends were declared and paid by the Company to its members in respect of the half year ended 30 June 2025 (2024: $nil).

Auditor’s Independence

The Directors obtained an independence declaration from the Company’s auditors, Ernst & Young LLP.

This directors’ report is made out in accordance with a resolution of the directors:

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Dated at Perth this 22^nd day of August 2025

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MAC Copper Limited

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Half year financial statements

for the six months ended 30 June 2025

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MAC Copper Limited

Half year financial statements

for the six months ended 30 June 2025

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MAC Copper Limited

Condensed consolidated statement of comprehensive income

for the six months ended

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The accompanying notes are an integral part of these condensed consolidated financial statements.

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MAC Copper Limited

Condensed consolidated statement of financial position

as at

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The accompanying notes are an integral part of these condensed consolidated financial statements.

The condensed consolidated financial statements were approved and authorised for issue by the Board of Directors on 22 August 2025 and signed on its behalf by:

Patrice Merrin

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MAC Copper Limited

Condensed consolidated statement of changes in equity

for the six months ended 30 June 2025 and 2024

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The accompanying notes are an integral part of these condensed consolidated financial statements.

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MAC Copper Limited

Condensed consolidated statement of cash flows

for the six months ended

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