Antofagasta Shares Fall on Lower Copper Output and Increased Cost Guidance

Shares in London-listed mining group Antofagasta (LSE:ANTO) fell sharply on Wednesday after the company reported a significant drop in first-half copper production and raised its cost guidance for the full year.

Production Misses Expectations

In its second-quarter production report, Antofagasta announced that its copper output for the first half of 2026 totaled 285,000 tonnes, a 9.5% decline compared to the same period in the previous year. The company attributed the shortfall to lower throughput at its key Los Pelambres and Centinela concentrator operations in Chile.

The weaker-than-expected performance has cast doubt on the company's ability to meet its full-year production target of 650,000 to 700,000 tonnes. Achieving this goal would require a substantial increase in production during the second half of the year.

Costs Rise Amid Sector Headwinds

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Compounding the production issues, Antofagasta revised its cash cost guidance upward. The company now expects costs before by-product credits to be in the range of $2.40 to $2.60 per pound, an increase from the previous forecast of $2.30 to $2.50 per pound. Management cited persistently high fuel prices and other key consumables as the reason for the revision.

In a statement, CEO Iván Arriagada said that "full-year guidance remains unchanged, with copper production expected to increase through the remainder of the year." However, the combination of lower output and higher costs weighed on investor sentiment. The stock fell 4.8% to trade at 3,658.5 pence, making it one of the worst performers on the FTSE 100 index.

Market Context

The decline came amid a broader sell-off in the mining sector, which led the FTSE 100 lower in morning trading. Weaker spot prices for copper, gold, and silver also created headwinds for commodity producers, removing a tailwind that had recently supported the sector.