The Antofagasta copper production cut announced alongside its first-half results has sent the miner’s shares down 4.9%, pulling London’s entire mining sector lower and making Antofagasta the worst performer on the FTSE 100 on Thursday morning.
The Chilean miner revised its full-year 2026 output guidance to between 625,000 and 655,000 metric tonnes, from a prior range of 650,000 to 700,000 tonnes. According to The Northern Miner, that represents a reduction of roughly 5% at the midpoint.
Los Pelambres shutdown: what triggered the Antofagasta copper production cut
The immediate cause was an orderly shutdown of the Los Pelambres processing plant and mining operations after intense precipitation and intermittent power outages that began late on 18 July 2026. Antofagasta’s own operational update described the group supporting local authorities through road clearance and emergency response across the Choapa Province.
The storm that forced the shutdown was no minor weather event. Reuters Connect reported that Chile’s government declared a state of catastrophe across both the Coquimbo and Atacama regions after the storm left at least 10 people dead, four missing, more than 1,100 homes destroyed, and over 100,000 people isolated.
Antofagasta said there has been no material impact on key equipment and infrastructure, though pipeline platforms and water management systems will require repair work before normal operations resume.
Strong cash flow cushions the blow, but the production trend is troubling
What makes this guidance cut genuinely awkward is the context in which it lands. Reuters reported that Antofagasta’s first-half 2026 core earnings rose 27%, with higher copper prices compensating for the volume shortfall. Cash flow from operations reached USD 2.77 billion in the first half, up from USD 1.81 billion in the same period a year earlier.
But the production numbers tell a different story. Morningstar/Alliance News reported that H1 2026 copper output came in at 285,000 tonnes, a 9% year-on-year decline, driven by lower production at both Los Pelambres and Centinela. Annual output has now fallen for two consecutive years: 664,000 tonnes in 2024, 653,700 tonnes in 2025, and now a revised ceiling of 655,000 tonnes for 2026 that could slip further if Los Pelambres takes longer to recover.
Capital expenditure for the first half was USD 1.67 billion, up marginally from USD 1.62 billion a year earlier, and full-year capex guidance was left unchanged at USD 3.4 billion. In other words, Antofagasta is spending at the same rate while producing less, at least for now.
Antofagasta is not alone in cutting its Chilean copper outlook. State-owned miner Codelco has lowered its 2026 production guidance to approximately 1.34 million tonnes from roughly 1.37 million tonnes, having already abandoned a more ambitious 1.7 million-tonne target set by its previous chief executive, Máximo Pacheco.
The market’s nervousness about Chile’s short-term production capacity is understandable. What is less clear is whether investors are right to punish the wider sector quite so sharply on the back of one weather event, however severe.
Rio Tinto fell 4.6%, Fresnillo dropped 4%, and both Endeavour and Anglo American shed more than 2.5%, declines that owe more to sentiment than to any operational news of their own. Mining equities have always traded as a pack, and the herd is moving today.
Antofagasta’s longer-term case rests on the expansion projects at Centinela and Los Pelambres, both of which are advancing towards commissioning completion in 2027 and are collectively expected to deliver a 30% increase in copper production. If those timelines hold, the current guidance cut looks more like a temporary setback than a structural one.
The repair timeline at Los Pelambres is the number to watch. Any extension into the fourth quarter would test the revised guidance range and, almost certainly, test the share price again.
