美国铜库存集中掩盖全球供应紧张

A growing concentration of copper inventories in US warehouses is masking tightening supplies elsewhere, creating a fragmented global market where a surplus can coexist with shortages and elevated prices, according to a study by GEM Mining Consulting.

Nearly 70% of the world’s visible exchange copper stocks are now held in the US, a dramatic shift from historical patterns, the study found. Global inventories reached 1.04 million tonnes in October, up 83% from a year earlier, but much of that metal is effectively separated from buyers in other markets.

The imbalance helps explain conflicting forecasts for 2026. The International Copper Study Group (ICSG) projects a global refined copper surplus of 104,000 tonnes, while Goldman Sachs estimates a deficit of roughly 950,000 tonnes outside the US and expects prices to reach $14,700 per tonne by year-end.

BMO Metals and Mining researchers have also flagged a widening disconnect between muted futures price movements and tightening physical supplies. Speculative positioning remains cautious ahead of the US midterm elections, even as China’s Yangshan cathode premium has climbed above $200 per tonne and Shanghai premiums for non-registered equivalent cathodes have reached record levels.

The divergence suggests that headline inventory figures are becoming a less reliable measure of copper availability, particularly as US trade policy encourages metal to remain in American warehouses while buyers elsewhere face rising costs.

Inventory imbalance

GEM’s Patricio Faúndez’s analysis, based on data from the Chilean Copper Commission (Cochilco), shows that COMEX warehouses held 718,000 tonnes of copper in October, accounting for 69% of visible stocks across the London Metal Exchange (LME), COMEX and Shanghai Futures Exchange (SHFE).

Between 2015 and 2024, COMEX accounted for an average of just 16% of exchange inventories, with its share never exceeding 36%.

The current stockpile is roughly double the exchange’s previous record in Cochilco’s historical series dating to 1990.

Meanwhile, combined LME and SHFE inventories stood at 319,000 tonnes, 11% below their 2015–2024 average.

That figure includes nearly 130,000 tonnes held in LME warehouses in New Orleans and Baltimore, according to press reports cited in the study. Excluding those stocks leaves approximately 190,000 tonnes of visible exchange copper outside the US.

The concentration accelerated after Washington launched a Section 232 investigation into copper imports in February 2025, prompting traders to move metal into the country ahead of potential tariffs.

Between February and July 2025, COMEX copper traded at an average premium of about $1,120 per tonne over LME prices, with the monthly spread reaching $2,230 in July.

The premium collapsed after Washington excluded refined copper cathodes from a 50% import tariff announced on July 30, 2025.

Yet the flow of metal continued.

According to Faúndez, 77% of the 633,000 tonnes added to COMEX inventories since February 2025 arrived after the tariff announcement, even though the price premium had fallen sharply.

From August 2025 through September 2026, the spread averaged just $156 per tonne, barely above its 2024 average of $151.

The findings indicate that tariff uncertainty, rather than immediate price arbitrage alone, has become a major factor keeping copper in the US.

Supply pressures

Washington has left open the possibility of imposing tariffs on refined copper of 15% in 2027 and 30% in 2028. A Commerce Department update was due in June 2026, but no subsequent decision has been published, according to the study.

With the current COMEX premium too small to justify shipping copper back overseas, traders have little incentive to reverse earlier shipments while future duties remain possible.

Physical market indicators in China suggest that supplies are tightening. BMO researchers pointed to record contract settlements for cathode premiums alongside the surge in Yangshan prices, suggesting buyers are paying increasingly high premiums to secure available material even as speculative investors remain cautious.

Supply risks are also emerging in Africa. BMI, a unit of Fitch Solutions, has warned that the Democratic Republic of Congo (DRC) and Zambia could face electricity shortages stemming from El Niño-induced drought, potentially disrupting copper production in two major producing countries.

The DRC is also tightening oversight of artisanal mining. Its mines minister recently suspended the official responsible for supervising the sector as authorities sought to curb unauthorized operations, following reports of hundreds of Chinese workers being arrested.

Although these developments have not established an immediate reduction in copper output, they add uncertainty to a market already showing signs of regional supply stress.

A trial shipment of 12,000 tonnes of Congolese copper into Project Vault, a US public-private strategic stockpile, further underscores Washington’s efforts to secure domestic metal supplies.

Faúndez’s study suggests the next major catalyst for copper prices will be the US decision on refined copper tariffs.

If Washington proceeds with duties, inventories could remain concentrated in American warehouses, sustaining tightness elsewhere and potentially widening the COMEX premium ahead of 2027.

If the tariffs are abandoned, some copper could return to international markets, putting downward pressure on LME prices and potentially pushing COMEX into a discount, as briefly occurred between January and March 2026.

The analysis does not provide an independent price forecast, but it highlights a growing challenge for the copper market: global supply balances may show a surplus while regional inventories, trade barriers and physical premiums point to a much tighter reality.