Northern Star stock plunges as miner forced to slash 2026 output on litany of plant and maintenance faults

A bout of plant failures and operational hiccups at Northern Star Resources’ WA operations in recent months has forced the heavyweight gold miner to cut expected output for the year. Australia’s biggest gold miner fessed up to the production disruption on Friday — the first day of trading in 2026 — revealing to the ASX that full-year guidance would have to be reduced from a 1700koz to 1850koz range to between 1600koz and 1700koz. Northern Star’s share price plummeted and closed 8.6 per cent lower to $24.43, its lowest since November, as investors gulped at the prospect of even higher costs for the year. The downgrade to its full-year gold sales comes as a result of what the miner said were a “number of isolated negative events coinciding” at its operations in WA and in the US during the December quarter. This included faults with its primary crusher at its anchor Super Pit operation in Kalgoorlie that have in turn been slowing down throughput into the processing plant over the past four weeks. While those issues are expected to be fixed in early January, even after that Northern Star has said throughput will be unpredictable for the next six months as it gets to the pointy end of building a brand new mill expansion project to boost annual processing capacity to 27mtpa. Northern Star said the $1.5 billion plant was on track for commissioning early in the 2027 financial year. Adding to the issues at its anchor KCGM operations, the miner has also had to fix a wall slip from October that occurred in the open pit at South Kalgoorlie. Northern Star told the market on Friday that the site had since returned to normal underground mining as of December. There’s also still headaches at its Yandal operations further north, with the impact of a structural failure in its crushing circuit at Jundee from the start of October now not expected to be fully fixed until the March quarter. A previously anticipated 10koz hit to production from that incident has risen to 20koz. And at Thunderbox, gold sales have been hampered by low grade ore from the Orelia open pit as well as fixing carbon-in-leach tank failures. Gold sales over at its Pogo operations in Alaska have also been dragged down due to grade issues. As a result, Northern Star ended the tumultuous December quarter with total output of 348koz, taking the the miner’s output for the first half of the 2026 financial year to about 729koz. The lower gold sales across the three production centres are likely to result in a hit to the group’s annual cost guidance that should be laid bare in a quarterly update to the market on January 22. Costs had already been on the mind of Northern Star watchers after the miner flagged in July that general inflationary pressures would push up all-in sustaining costs for 2026 and land between $2300/oz and $2700/oz. The miner will brief investors on the downgrade before that on January 5. Northern Star has a buoyant gold price in its corner, with the stock reaching record highs at the end of December. Revenues were up 30 per cent to $6.4 billion in the previous financial year as its average gold sale price rose 29 per cent to $3922 an ounce.