A growing concentration of copper inventories in United States warehouses is masking tightening supplies everywhere else, according to a study by GEM Mining Consulting reported by Mining.com. Global visible exchange inventories reached 1.04 million tonnes in October, up 83 percent from a year earlier, but nearly 70 percent of that metal sits in the United States, effectively separated from buyers in other markets.
The split is stark in the study’s numbers, which draw on data from Cochilco, the Chilean Copper Commission. COMEX warehouses held 718,000 tonnes in October, 69 percent of visible stocks across the London Metal Exchange, COMEX and the Shanghai Futures Exchange, against an average share of just 16 percent between 2015 and 2024 and a previous record roughly half the current level in a series dating to 1990. Combined LME and SHFE inventories stood at 319,000 tonnes, 11 percent below their 2015 to 2024 average, and excluding nearly 130,000 tonnes held in LME warehouses in New Orleans and Baltimore leaves only about 190,000 tonnes of visible exchange copper outside the United States.
That is why the forecasts disagree so widely. The International Copper Study Group projects a global refined copper surplus of 104,000 tonnes for 2026, while Goldman Sachs estimates a deficit of roughly 950,000 tonnes outside the United States and expects prices to reach 14,700 dollars a tonne by year end. BMO researchers have flagged the same disconnect, noting muted futures moves against tightening physical supplies, with China’s Yangshan cathode premium above 200 dollars a tonne and Shanghai premiums for non registered cathodes at record levels.
The cause, on the study’s reading, is policy rather than price. The inflow accelerated after Washington opened a Section 232 investigation into copper imports in February 2025, and 77 percent of the 633,000 tonnes added to COMEX inventories since then arrived after refined cathodes were excluded from the 50 percent tariff announced on July 30, 2025, even as the COMEX premium over London collapsed from an average of about 1,120 dollars a tonne to about 156 dollars. With Washington still able to impose refined copper tariffs of 15 percent in 2027 and 30 percent in 2028, and no Commerce Department decision published since the June 2026 update deadline, traders have little incentive to ship the metal back out. US copper in the site market tables eased 0.86 percent to 6.52 dollars a pound on the day.