Mercury Quarterly Operational Update

>> QUARTERLY HIGHLIGHTS

>> COMMENTARY

Market summary

National hydrological inflows of 62nd percentile during the quarter contributed to lower spot electricity prices averaging $216/MWh in Auckland. Forward electricity prices have eased to $179/MWh in Auckland for financial years 2026 to 2027 as of 30th June 2025.

FY25 hydro generation the 4th lowest from the Waikato scheme since 1980

Total generation for FY25 was 7,906GWh (874GWh, 11% lower than PCP). This primarily reflects lower hydro generation of 3,410GWh (686GWh, 17% lower than PCP) driven by 12th percentile Waikato catchment inflows and a lower than average Lake Taupō starting level. Lower wind generation of 1,936GWh (125GWh, 6% lower than PCP) from lower wind speeds and lower geothermal generation of 2,559GWh (63GWh, 2% lower than PCP) from planned outages contributed to the lower FY25 total generation.

For the quarter, a low Lake Taupō level and dry conditions to start the period contributed to lower hydro generation of 864GWh (155GWh, 15% lower than PCP). High hydro inflows at the end of the quarter increased Waikato catchment inflows to 79th percentile for the period, providing a healthy hydro storage leading into FY26.

Increasing mean hydro generation from Digital River and Karāpiro Rehabilitation

Looking ahead, Mercury's average annual hydro generation has increased 62GWh to 4,140GWh per annum. The uplift in the mean hydro expectations is driven by the Karāpiro Rehabilitation Project and the Digital River, Mercury's AI-powered decision platform and digital twin. The Digital River optimises hydro operations by simulating complex hydrology scenarios for value and has already contributed to record high hydro efficiency in FY25.

Karāpiro project concluding with third unit

Mercury is anticipating the completion of the full replacement of the third generating unit at Karāpiro hydro station in Sep-25, concluding the three-year programme of work at the site. The full replacement of the three units at Karāpiro increases hydro capacity by 16.5MW, resulting in 32GWh of additional generation assuming average inflows.

>> OPERATING STATISTICS

OPERATING INFORMATION

Notes:

• Includes LPG bottle connections
• Includes mobile
• VWAP is volume weighted average energy-only price sold to customers after lines, metering and fees
• Mass market includes residential segments and non time-of-use commercial customers
• Fixed-price, variable-volume (FPVV) sales to time-of-use commercial customers
• Excludes spot customer purchases
• Includes Virtual Asset Swap volumes of 37 GWh for the 3 months ended 30 June 2025 and 75 GWh for the 3 months ended 30 June 2024 and of 225 GWh for the 12 months ended 30 June 2025 and 376 GWh for the 12 months ended 30 June 2024. Also includes the Manawa CFD volumes relating to the Trustpower retail transaction since May 2022
• Includes Mercury's 65% share of Nga Awa Purua generation
• Includes all physical and financial buys and sells except spot customer purchases and wind ppa

>> MARKET DATA

ELECTRICITY GENERATION BY COMPANY FOR THE THREE MONTHS ENDED 30 JUNE

Financial Year Q4 2025

Mercury: 28%, Meridian Energy: 19%, Contact Energy: 17%, Genesis Energy: 14%, Manawa Energy: 2%, Other: 17%

Financial Year Q4 2024

Mercury: 20%, Meridian Energy: 30%, Contact Energy: 19%, Genesis Energy: 11%, Manawa Energy: 3%, Other: 17%

Source: Transpower SCADA

SHARE OF ELECTRICITY SALES (GWh) FOR THE THREE MONTHS ENDED 30 JUNE (EXCLUDING CFDs)

Financial Year Q4 2025

Mercury: 82%, Other: 18%

Financial Year Q4 2024

Mercury: 82%, Other: 18%

Source: Mercury Purchases and Transpower SCADA

OTA HUHU WHOLESALE PRICE AND NATIONAL HYDRO STORAGE LEVELS

Chart Description: Line graph showing Average National Storage (GWh), FY2025 National Storage (GWh), Average Monthly OTA Spot Price ($/MWh), FY2024 National Storage (GWh), and Rolling 12 Month Average OTA Spot Price ($/MWh) from July to June.

Source: NZX Hydro and NZEM Pricing Manager (NZX)

TAUPO STORAGE

Chart Description: Line graph showing Taupō Storage (GWh) for Average Since 1999, FY2024, and FY2025 from July to June.

Source: NZX Hydro

OTAHUHU ASX FUTURES SETTLEMENT PRICE

Chart Description: Bar chart showing Otahuhu ASX Futures Settlement Price ($/MWh) for Financial Years 2025, 2026, and 2027, with data points for As at 30/09/2024, As at 31/12/2024, As at 31/03/2025, and As at 30/06/2025.

Source: ASX

BENMORE ASX FUTURES SETTLEMENT PRICE

Chart Description: Bar chart showing Benmore ASX Futures Settlement Price ($/MWh) for Financial Years 2025, 2026, and 2027, with data points for As at 30/09/2024, As at 31/12/2024, As at 31/03/2025, and As at 30/06/2025.

Source: ASX

NATIONAL CONSUMPTION (NON-TEMPERATURE ADJUSTED)

Chart Description: Bar chart showing National Consumption (GWh) and Tiwai Point Aluminium Smelter Consumption (GWh) for Q4 2020 through Q4 2025.

Source: Transpower Information Exchange

AUCKLAND CLIMATE SUMMARY (°C)

Source: Met Service

MONTHLY TOTAL CONSUMER RETAIL SWITCHING (ICPs)

Chart Description: Dual-axis line graph showing NZ Market Churn (LHS, ICPs) and Annual NZ Market Churn % (RHS) from July 2021 to the present.

Source: Electricity Authority