Mining stocks across the FTSE 100 suffered sharp declines during the week ending 14 August 2026, with major players shedding billions in combined market value.
Antofagasta (LSE: ANTO), Glencore, and Anglo American each fell around 3% to 5% on Thursday 13 August, dragging the wider FTSE 100 index down almost 150 points for the week.
Endeavour Mining, Rio Tinto, and Fresnillo were also caught in the downdraft, though their losses were more modest at 0.7%, 1.4%, and 1.1% respectively.
The six firms together contribute around £284.4bn to the UK market, with Thursday’s combined losses resulting in approximately £6.9bn in erased value.
Some of those losses were recovered by the close of trading, but the episode underscores how heavily the domestic economy depends on the performance of its mining sector.
Antofagasta, one of the UK’s most prominent pure-play copper miners, sits at the centre of the selloff after releasing its first-half results on Thursday.
The company reported an 18% revenue jump and pre-tax profit up 72% to $2bn, with earnings per share climbing 62% to 85.9c and a substantial 81% dividend increase to 30.1c per share.
Despite those impressive figures, investors focused instead on Antofagasta’s decision to cut its 2026 copper-production forecast to 625,000-655,000 tonnes, down from a prior guidance range of 650,000-700,000 tonnes.
The downgrade followed severe rain and snowfall in Chile, which temporarily shut the company’s Los Pelambres mine and damaged pipeline platforms and water-management infrastructure.
First-half copper output came in at 285,000 tonnes, down approximately 9% year on year, principally because of weaker production at Los Pelambres and Centinela.
The lower guidance implies a reduction of roughly 5% at the midpoint, raising concerns about lower copper sales volumes, potentially higher unit costs, repair and remediation expenditure, and increased weather risk for the remainder of winter in Chile.
Antofagasta produced approximately 653,700 tonnes of copper in 2025, and operates four mines across Chile, making it highly sensitive to local operating conditions and commodity price movements.
The company operates with significant exposure to Chilean weather patterns, and Thursday’s results demonstrated clearly how environmental events can overshadow even strong financial performance in investor sentiment.
Antofagasta says its Centinela and Los Pelambres projects remain on track and are expected to support a substantial production increase from 2027 onwards, offering some longer-term reassurance to shareholders.
For risk-tolerant investors, the share price dip following strong underlying financial results could represent a buying opportunity, though the operational risks tied to Chilean weather and infrastructure remain a live concern.
Mining remains a critical part of the global economy, supplying raw minerals used in construction, manufacturing, technology, energy, and agriculture, and its outsized influence on the FTSE 100 was plain to see this week.
The broader retreat in mining shares coincided with weakening sentiment around copper and industrial metals more generally, amplifying the pressure on individual stocks beyond Antofagasta’s company-specific news.
Investors weighing up exposure to the sector will need to balance Antofagasta’s strong earnings trajectory against the unpredictable environmental risks inherent in operating large-scale open-pit mines in the Andes.