Quarterly Operational Update

Quarterly Operational Update for the three months ended 30 September 2024. QUARTERLY HIGHLIGHTS > MARKET REACTS TO HIGH PRICES - evidenced by the demand and fuel response. > TAUPO LAKE LEVEL NOW NORMAL - despite low starting lake level and inflows in Q1. > C&I ELECTRICITY YIELD GROWTH - repricing to a sustained higher forward curve. COMMENTARY MARKET SUMMARY Near record low national hydro storage and persistent gas supply constraints contributed to the tight electricity market in July and early August, resulting in record high spot electricity prices for the first half of the quarter. The situation eased from mid-August due to unseasonally wet conditions in the South Island, which led to major hydro lakes returning to normal levels. This, along with increased gas volume for generation and sector demand response, resulted in a significant reduction in wholesale spot prices in the second half of Q1 and into Q2. Whilst national demand was 2.5% lower for the quarter relative to PCP due mostly to NZAS’ demand response, actual demand, normalised for the short-term industrial response, would have increased by 0.9%. National hydrological inflows for the period were 88th percentile, belying the drought conditions at the start of the quarter, resulting in spot prices averaging $298/MWh in Auckland. Forward prices remain elevated, averaging $193/MWh in Auckland for financial years 2025 to 2027. LOWER HYDRO GENERATION PARTIALLY OFFSET BY HIGHER WIND GENERATION AND GEOTHERMAL PERFORMANCE Dry Waikato catchment conditions with 19th percentile inflows saw Q1 hydro generation reduce to 965GWh (179GWh, 16% lower than PCP). Wind generation was higher at 549GWh (19GWh, 4%  higher than PCP) due to the full quarter impact of the new Kaiwera Downs 1 wind farm. Improved performance in geothermal generation resulted in 22GWh higher generation than PCP at 683GWh. Commercial & Industrial yield growth (physical and end-user CfDs) was $17/MWh higher for the quarter relative to PCP because of contract repricing to a sustained higher electricity forward curve. We are forecasting hydro generation of 3,900GWh for the financial year, an increase of 100GWh from August guidance. SPOT GAS PRICES SHADOW ELECTRICITY SPOT PRICES Daily wholesale spot gas prices peaked at $54/GJ within the quarter, and subsequently reduced as short-term gas availability increased after Methanex on-sold gas and idled their plant from mid-August. Mercury’s higher gas purchase price of $28.6/GJ for the quarter was $14.7/GJ higher than PCP and reflects ongoing spot gas exposure. [For Operational Statistics and Charts, please refer to the attached] ENDS Howard Thomas General Counsel and Company Secretary Mercury NZ Limited For investor relations queries, please contact: Paul Ruediger Head of Business Performance & Investor Relations 027 517 3470 investor@mercury.co.nz For media queries, please contact: Shannon Goldstone Reputation & Social Impact Lead 027 210 5337 mercurycommunications@mercury.co.nz