Antofagasta Minerals Lifts Q3 Copper 7% but Costs Rise, Shares Fall

Antofagasta Minerals lifted copper output 7% quarter on quarter to 151,900 tonnes in its Q3 production report on 15 October 2026. The market still marked the result down. Nine-month output remains 8.3% below 2025, and the company raised its full-year cost guidance on the same day.

The Chilean miner went into the quarter with two problems. A severe storm forced a shutdown at Los Pelambres in July, and ore grades at Centinela (the amount of copper contained in each tonne of rock) kept falling.

The rebound was largely arithmetic. A weak second quarter set a low base, and some of the July losses came back as released inventory. The year’s direction has not changed.

Here is why a 7% gain still disappointed, what the higher costs and the 2027 range signal, and what has to go right for the investment case to hold.

Why did a 7% copper rebound still disappoint the market?

On the quarterly comparison, the numbers look healthy. Copper rose from 142,000 t in Q2 to 151,900 t, the strongest quarter of the year so far.

The year-to-date figures tell a different story.

Nine-month copper shortfall 436,900 t produced in 2026, against 476,600 t in the same period of 2025, a fall of 8.3%.

By-products also weakened. Nine-month gold fell 5.4% and molybdenum fell 21.1%.

Brokers had expected more. According to analyst commentary reported on the day, Peel Hunt had pencilled in about 158,000 t for Q3 and kept a Hold rating with a full-year estimate of 642,000 t. RBC and J.P. Morgan were both reported to see output below consensus, and RBC analysts said 2027 guidance implies no growth on the company’s original 2026 guidance. The shares fell on the news.

Management kept 2026 copper guidance at 625,000-655,000 t. If you hold or follow the stock, that tells you the company still believes the year is recoverable. It also means Q4 has to run well above the nine-month pace.

Antofagasta is not alone in its nine-month shortfall, as other large Chilean miners have also reported falling output tied to ageing orebodies and declining grades.

What drove the swing: Los Pelambres, Centinela and a fuel-driven cost reset

Los Pelambres: recovery, with caveats

The storm hit late on 18 July. Heavy rain and power outages forced an orderly shutdown, and operations restarted on 23 July. Earlier disclosures noted that Chile declared the Coquimbo region a state of catastrophe. Inspections found no material damage to key equipment, although pipeline platforms and water systems needed repairs.

Extreme weather risk has become a recurring feature of Chilean copper supply, and the July shutdown at Los Pelambres is a reminder that water and power infrastructure can halt output within hours.

Even so, Los Pelambres drove the quarter. Copper output rose 17.5% to 79,300 t on better recoveries (the share of copper extracted from processed ore) and about 7,000 t of released inventory, while throughput stayed constrained.

Centinela: the structural drag

Centinela Concentrates moved the other way. Q3 output slipped 5% to 32,300 t as grade eased to 0.42% and recovery to 80.5%. Nine-month output is down about 19% to 143,900 t.

The company said the lower grade matches the mine plan. In other words, this is not weather damage that will reverse.

Pre-credit cash costs (the cost to produce a pound of copper before by-product sales are deducted) fell to $2.73/lb in Q3. Over nine months, however, they are about 20% higher at $2.81/lb. The causes were:

• Higher diesel prices
• Higher sulphuric acid costs
• Lower production spread over fixed costs
• Partly offset in Q3 by settlement of the Centinela labour agreement and lower treatment charges

Net cash costs, which deduct gold and molybdenum sales, came in at $1.38/lb for the quarter, just above the top of the guided range.

The cost increase tells you the pressure is lasting beyond one bad quarter. Margins now lean on copper prices holding up, and Q3’s realised price was $6.79/lb.

Can 2027 projects and copper fundamentals carry the recovery?

Projects and guidance

Antofagasta guided 2027 copper output to 630,000-690,000 t. That range assumes higher Los Pelambres grades, lower Centinela grades, and commissioning in 2027 of the Centinela Second Concentrator and the Los Pelambres pipeline and desalination expansion. The Centinela primary crusher and overland conveyor began pre-commissioning in Q3.

Executive Chairman Iván Arriagada pointed to demand rising on electrification and digitalisation, with no significant short-term increase in global supply expected. Peel Hunt’s 2027 estimate of about 710,000 t sits above the guided range. Cost and capex guidance for 2027 is due with the Q4 report in January 2027.

Investors weighing the 2027 commissioning risk can read our full explainer on the Centinela expansion investment, which sets out how the second concentrator is meant to extend mine life.

A divided copper market

The Q3 average market price was $6.40/lb, and spot reached $6.57/lb on 30 September. Forecasters disagree on what comes next.

ICSG expects refined production growth of 3.4% in 2027 to outpace usage growth of 2.5%. The main company-specific risks are:

• Delays to 2027 commissioning
• Water and weather exposure at Los Pelambres
• Continued grade decline at Centinela
• A strike declared after the quarter by two Centinela unions representing about 20% of own employees

Because the guided range sits below some broker estimates, treat 2027 as an execution story. On-time commissioning matters more than commentary on copper prices.

The Q4 test that decides whether the rebound holds

The Q3 rebound was real, but it was mechanical. The nine-month shortfall and higher costs have not gone away, and the investment case now rests on delivery.

There are four checkpoints. The first is whether Q4 output lifts the full year into the 625,000-655,000 t range. The second is the January 2027 release of 2027 cost and capex guidance. The third is how the Centinela strike is resolved, and the fourth is commissioning progress at both flagship projects.

This article is for informational purposes only and should not be considered financial advice. Investors should conduct their own research and consult with financial professionals before making investment decisions. Past performance does not guarantee future results. Financial projections are subject to market conditions and various risk factors.