Copper prices steadied on Wednesday after sliding to their lowest in about 2-1/2 months, but metal kept piling up in London Metal Exchange warehouses, where stocks climbed to 312,250 metric tons, the most since early July.

The LME's official cash price rose 0.64% to $14,201 a ton on Wednesday and the three-month price gained 0.67% to $14,095, according to the daily report of Cochilco, Chile's state copper commission. A day earlier, three-month copper touched $13,883, its lowest since Aug. 19, Reuters reported. That left it nearly 7% below September's record of $14,875.

For Asian buyers, the warehouse numbers say more than the price. Copper is accumulating in the West, mostly in the U.S., while exchange stocks in China are shrinking and Chinese importers are paying the highest premiums in more than a decade. China accounts for 57.3% of world copper demand, according to Cochilco.

LME stockpile builds in U.S. warehouses

LME copper stocks rose a further 2,600 tons in Wednesday's report after jumping 15,875 tons on Tuesday, according to LME data compiled by Cochilco and Westmetall. Holdings are up 38.5% since Oct. 16, when they stood at 225,425 tons.

Tuesday's rise was driven by an inflow of 17,325 tons into LME-registered warehouses in the U.S., Reuters reported. Ed Meir, an analyst at the broker Marex, told the news agency he suspected copper was "catching up" with the sell-off in AI-linked chip stocks.

The U.S. already holds most of the copper in exchange warehouses. Stocks on New York's Comex stood at 731,430 tons on Nov. 3, Cochilco data show. In its weekly report for the week to Oct. 30, the commission said Comex held 69.5% of the copper in the three main exchanges' warehouses, and that its stocks were more than six times their level a year earlier.

That build-up followed months of uncertainty over possible U.S. tariffs on refined copper imports, which drew cargoes to the country. The World Bank said in its October outlook that uncertainty over tariffs that could take effect in January may encourage more stockpiling and regional shortages, Mining.com reported. Cochilco, for its part, said less U.S. stockpiling could redirect shipments and ease shortages elsewhere without any rise in global consumption.

The extra metal has eased tightness in London. The premium of LME cash copper over the three-month contract, a gauge of near-term scarcity, reached $210 a ton on Oct. 29, according to Cochilco. By Wednesday it had roughly halved to about $106, based on the official prices in the commission's daily report.

Shanghai stocks shrink as China pays up

China shows the reverse pattern. Copper stocks in Shanghai Futures Exchange warehouses fell 17.9% in the week to Oct. 30, to 44,612 tons, and were 58.5% lower than a year earlier, Cochilco said. Shanghai Metals Market estimated Chinese commercial inventories at 66,900 tons on Oct. 29, down 24,700 tons in a week, the commission added.

The Yangshan premium, which measures what buyers pay for imported copper over the LME price, rose to $205 a ton in late October, according to Cochilco, a level Reuters described as a 13-year high. It was still near $200 on Tuesday, Reuters reported.

Cochilco warned against reading the drawdown as a sign of booming demand. It said the fall in Chinese stocks reflected fewer arrivals, logistics delays and contractual supply limits, and that high prices and premiums had kept fabricators buying only for immediate needs. The commission expects growth in Chinese copper demand to slow to 1.0% in 2027 from 1.6% this year.

Currency moves added to the cost. The yuan weakened sharply after the People's Bank of China said it would raise the foreign-currency reserves that financial institutions must hold, making dollar-priced metal more expensive for Chinese buyers, Reuters reported on Tuesday.

Thin supply keeps prices high

Mine output remains the main support for prices. Chile's copper production fell 15% from a year earlier in September, Reuters reported, and Cochilco expects the country's output to drop 8.4% this year to 4.94 million tons. Even so, the commission projects only small refined surpluses: 144,000 tons in 2026, about 0.5% of world consumption, widening to 215,000 tons in 2027.

LME cash copper has averaged $13,558 a ton so far this year, 39.9% above the same period of 2025, Cochilco data show. Its November average to date, $14,231, is below October's $14,532.

In New York, the front-month Comex contract settled at 637.85 cents a pound on Tuesday, Cochilco data show, close to Wednesday's LME three-month price of about 639 cents. Tariff worries had earlier lifted Comex prices above London's, but the World Bank said that gap had narrowed substantially by September.

Most other LME metals rose on Wednesday after a broad sell-off on Tuesday. Cash nickel rose 1.74% to $15,465 a ton, aluminum gained 1.72% to $3,135 and tin added 0.46% to $48,125, Cochilco data showed. Tin had dropped 4.3% on Tuesday to $47,450 after touching its lowest since mid-April, Reuters reported. Indonesia's refined tin exports fell 18% from a year earlier in September, the news agency said.

The Shanghai Futures Exchange publishes its next weekly stock figures on Friday, Nov. 6, the first read on whether Chinese inventories are still falling while metal keeps arriving in LME warehouses in the U.S.