Antofagasta PLC (LSE:ANTO) shares dropped 4% as the FTSE 100 mining giant warned that annual production will be at the lower end of previous guidance.
The company's shares, which hit an all-time high above 2,400p in May after rising more than 150% over the past five years, fell 86p to 2,042p on Wednesday morning.
The Chilean copper colossus said total production for 2024 would therefore be nearer to 670,000 tonnes than 710,000 tonnes, which was the guidance range given earlier in the year.
This was due to lower grades at its Los Pelambres and Centinela copper mines in the second quarter, though total copper production was up 20% compared to the first quarter at 155,300 tonnes.
Output for the first half of 2024 was down 3.7% on the level seen a year ago, after lower grades at both Los Pelambres and Centinela, though Los Pelambres enjoyed higher ore processing volumes in the past quarter following a recently completed expansion project.
CEO Iván Arriagada said production in the second half of the year is expected to include drawdowns from Los Pelambres' concentrate inventories that accumulated in February.
At Centinela, production in the second quarter reflected lower recoveries that were impacted by elevated levels of clay and fines in ores processed.
Arriagada said the company has consistently invested throughout the commodity cycle in order to deliver growth and build a portfolio of long-life mines.
He pointed to construction work ahead of schedule to build Centinela's second concentrator, while the first phase of the expansion of Los Pelambres has ramped-up to nameplate capacity, with work underway to double the capacity of the desalination plant and to construct a new pipeline.
"Taken together, these investments will add both growth and long-term security to the future of our portfolio at a time when there is strong and widespread recognition of copper's fundamental role in the energy transition," he said.