U.S. Copper Stockpiles Hit 1.6M Tonnes as Tariff Risk Lingers

U.S. copper inventories have climbed above 1.6 million tonnes as tariff expectations redirected metal into American warehouses. With COMEX stocks unusually elevated, traders are watching whether future policy changes could again trigger the kind of sharp market adjustment seen in 2025.

By Paul Ploumis
Published October 19, 2026

SEATTLE (Scrap Monster): Copper futures have rallied strongly over the past year, reached record territory and more recently settled into a comparatively sideways trading pattern. December COMEX copper closed Friday, October 16, at approximately $6.57 per pound.

Behind the quieter price action, however, an unusually large amount of copper has accumulated in the United States.

That stockpile does not necessarily reflect weak industrial consumption. Much of the metal was drawn into the U.S. by tariff expectations and price differences between COMEX and international copper markets.

Why So Much Copper Moved to the United States

U.S. copper inventories have grown to more than 1.6 million metric tonnes, including exchange stocks and copper held in other commercial storage facilities, according to a Reuters report cited by Barchart.

Much of the buildup occurred as traders anticipated possible U.S. import tariffs on copper.

When copper traded at a premium on COMEX relative to international markets, importing metal into the United States became an attractive arbitrage opportunity.

The movement therefore reflected trading economics and uncertainty over future trade policy rather than simply copper being purchased for immediate industrial consumption.

The result has been an unusually large concentration of copper in U.S. warehouses while visible supplies outside the United States have remained comparatively tighter.

Regional price differences are common in commodity markets. Transportation costs, local demand, warehouse availability and trade policy can all cause COMEX and London Metal Exchange copper prices to diverge, creating incentives to move metal from one market to another.

COMEX Inventories Far Exceed Shanghai Stocks

China remains the world's largest copper-consuming country, but its government strategic-reserve holdings are not publicly disclosed. That makes a full comparison between U.S. and Chinese copper inventories impossible.

Exchange inventories provide a more transparent comparison.

On October 9, copper inventories monitored by the Shanghai Futures Exchange stood at approximately 58,744 tonnes.

By mid-October, copper held in COMEX-approved U.S. warehouses exceeded 700,000 tonnes.

That means COMEX warehouses held roughly 12 times the copper reported in Shanghai exchange warehouses.

The comparison does not include China's government reserves or all privately stored material in either country. It does, however, illustrate the unusual scale of copper currently concentrated in U.S. exchange warehouses.

The 2025 Copper Collapse Shows the Policy Risk

The current inventory buildup has revived memories of the sharp market reversal in July 2025.

During the first half of that year, expectations of broad U.S. copper tariffs encouraged traders to ship large quantities of refined copper into the United States. The resulting arbitrage pushed COMEX copper to a substantial premium over London prices.

On July 30, 2025, President Donald Trump announced a 50% tariff on certain semi-finished copper products and copper-intensive derivatives, while refined copper such as cathodes was excluded.

The narrower-than-expected tariff surprised the market.

COMEX copper futures subsequently plunged by roughly 22% as traders rapidly reassessed positions, while the large U.S. premium over London copper disappeared.

The move was primarily a reaction to the unexpected tariff structure rather than a sudden collapse in global copper consumption.

Future Refined Copper Tariffs Remain a Market Variable

Trade-policy uncertainty has not disappeared.

The 2025 copper proclamation contemplated possible tariffs on refined copper of 15% beginning in 2027 and 30% beginning in 2028, subject to further review and presidential action.

That possibility has helped preserve an incentive for some copper to remain in the United States.

However, the current COMEX premium over international copper prices is substantially smaller than the extreme spread seen before the July 2025 market collapse.

Large Inventories Do Not Automatically Mean Lower Copper Prices

The U.S. stockpile is substantial, but inventory alone does not determine copper's direction.

Mine disruptions, global demand, Chinese consumption, visible inventories outside the United States, the COMEX-LME price spread and future U.S. tariff decisions will all influence the market.

The distinction between inventory accumulated because of weak demand and inventory accumulated because of arbitrage is particularly important. Much of the current U.S. copper buildup reflects trade-policy expectations and regional pricing rather than a straightforward deterioration in copper consumption.

For traders and physical-market participants, the key question is therefore not simply how much copper is sitting in U.S. warehouses, but what eventually changes the incentive to keep it there.

What the Market Is Watching

December copper finished October 16 at approximately $6.57 per pound after trading close to record territory earlier in the year.

On September 9, COMEX copper reached an intraday high near $6.89 per pound. The October 16 close left the contract roughly 4.6% below that level.

Whether the recent consolidation develops into another advance or a deeper correction remains uncertain.

U.S. inventories, the COMEX-LME price differential and future tariff decisions remain important indicators to watch as the market determines whether America's copper stockpile stays in place or eventually begins moving back into international markets.

Courtesy: www.barchart.com