A U.S. tariff regime designed to rebuild domestic copper capacity is instead enriching arbitrage traders, draining global supply, and doing nothing to fix the smelting bottleneck it was supposedly designed to address.
In the spring of 2026, more than half a million tonnes of copper are sitting in warehouses along the Mississippi River in New Orleans. COMEX inventories recently set an all-time record of over 603,000 short tons, representing roughly half of all visible global exchange stocks. Meanwhile, European and Asian manufacturers are paying record regional premiums for a metal they cannot source at reasonable prices. The London Metal Exchange, once described by traders as the copper market of last resort, has watched its available inventory shrink dramatically since 2025, leaving what remains dominated by Russian and Chinese brands that Western buyers are reluctant to touch. This is not a story of global copper scarcity. It is a story of one of the most consequential policy-driven inventory misallocations in the history of commodity markets.
The sequence began in February 2025, when the Trump administration launched a Section 232 national security investigation into copper imports. The stated goal was coherent enough: the United States consumes roughly 1.6 million metric tons of refined copper annually while producing only about 5% of the world's refined output, a strategic vulnerability that policymakers argued required correction. On July 8, 2025, President Trump announced a 50% tariff on all copper product imports, triggering what Nasdaq Sprott data described as copper's largest single-day price gain since 1968, with COMEX futures jumping more than 13% in a single session.
What followed was less a policy response than a gold rush. Traders, smelters, and institutional investors began physically redirecting copper toward CME-deliverable U.S. warehouses at an extraordinary rate. Weekly U.S. imports of refined copper surged from approximately 14,000 tonnes per week before the investigation to roughly 40,000 tonnes per week by late March 2025, according to Morgan Stanley analysts. By year-end, total 2025 U.S. copper imports had reached 1.4 million tonnes, compared to 921,000 tonnes for all of 2024. COMEX inventories rose more than 300% during the year to above 400,000 tonnes.
The policy structure that emerged on August 1, 2025, however, was not what markets had anticipated. Rather than a blanket tariff, the administration implemented a selective framework: a 50% duty on semi-finished copper products and intensive copper derivatives, while refined copper cathodes from key partners including Chile and Canada were largely exempted. The market had priced in a blunt instrument; it got a scalpel with an unsteady hand. COMEX futures fell roughly 19% from their July spike as the selective architecture was gradually understood.
What the tariff architecture actually created was a self-sustaining arbitrage machine. When the COMEX-LME price spread becomes wide enough to cover transport and financing costs, it is profitable to ship copper from Asia or South America to U.S. warehouses rather than sell it locally. At its peak in mid-2025, the COMEX premium over LME reached approximately $2,520 per tonne, a spread that comfortably justified the physical redirection. Even after the August refinements to the policy, the risk of future tariff expansion, with a formal June 30, 2026, review built into the executive order to consider phased refined copper duties of 15% starting in 2027 and 30% in 2028, has been sufficient to keep the arbitrage partially open.
By late April 2026, COMEX copper inventories had climbed back to within 1,000 tonnes of their all-time record, reaching 544,887 tonnes. The global head of metals at Mercuria, one of the world's largest commodity traders, noted publicly that more copper would continue flowing to the U.S. at least until July 2026, when the next major tariff decision is expected.
The consequences for the rest of the world have been significant. LME inventories in Asian storage hubs were drained substantially through 2025. Chilean copper exports to the U.S. rose 28% while exports to Europe and China fell sharply. China, which represents over 50% of global copper demand, saw its imports of refined copper fall 5% year-over-year and 20% quarter-over-quarter in early 2025 as metal was diverted to U.S. ports. ING commodities strategist Ewa Manthey described the result plainly: "It's like an artificial tightness right now in the markets because you have all this material in the U.S., but not enough outside of the U.S."
Into this distorted inventory picture, a cascade of genuine supply disruptions arrived. In May 2025, the Kamoa-Kakula mine in the Democratic Republic of Congo, one of the largest copper operations on the planet, experienced severe flooding that revised production guidance downward for 2026 and 2027. In July 2025, Codelco's El Teniente mine in Chile, the world's largest underground copper mine producing approximately 400,000 metric tons annually, suffered a fatal tunnel collapse. El Teniente's general manager, Claudio Sougarret, subsequently stated that production would remain depressed for the next five years as a result. Then, on September 8, 2025, a massive mudslide struck Freeport-McMoRan's Grasberg mine in Indonesia, the world's second-largest copper operation, which contributes roughly 4% of global supply. Freeport declared force majeure and cut its 2026 production forecast by 35%. Full recovery is not expected until 2027.
Benchmark Mineral Intelligence estimated that Grasberg alone would lose approximately 591,000 tonnes of contained copper output between September 2025 and end of 2026. Goldman Sachs revised total global copper mine supply downward by 160,000 tonnes for the second half of 2025 and 200,000 tonnes for 2026 following the Grasberg incident. ING's Commodities Outlook 2026 summarized the combined effect: a refined copper deficit of approximately 600,000 tonnes for 2026, following a 200,000-tonne shortfall in 2025.
The result is a market with a surreal texture. Global exchange inventories as of early 2026 topped one million tonnes, the highest since 2003, while copper was simultaneously in a structural supply deficit. J.P. Morgan forecast a refined copper shortfall of around 330,000 tonnes for the year. Copper futures on the LME reached above $13,000 per tonne in early 2026, a record high, while COMEX simultaneously held over half a million tonnes in storage. The price signal, which should guide physical allocation to where it is most needed, had been severed from physical reality by the distortions the tariff framework created.
The stated rationale for the Section 232 copper tariffs was to address U.S. strategic vulnerability: too dependent on imports, too little domestic smelting capacity, too exposed to foreign supply chain disruptions. The logical target of any corrective policy would be that smelting gap. The United States mines approximately 1.2 million tonnes of copper annually, but domestic smelting capacity handles only around 585,000 tonnes per year, leaving a processing gap of approximately 615,000 tonnes that must be exported to Mexico, Canada, Japan, and China for conversion into refined metal. The country has just two operating primary copper smelters, and both are running near full capacity.
The World Resources Institute, in an analysis of the tariff architecture, identified the core contradiction: rather than incentivizing new smelter construction, the policy created conditions where U.S. mines export raw concentrate abroad, which then returns as refined cathode subject to the very tariffs the framework was supposedly designed to reduce. Richard Holtum, CEO of commodity trading giant Trafigura, made the hierarchy explicit: "Mining is not critical, refining and smelting is critical. If you don't have it in your country, then you are at the mercy of someone that does."
Building a new copper smelter costs between $1.8 billion and $2.5 billion, requires years of permitting, and requires sulphur-capture and acid-plant systems to meet modern environmental standards. In 2025, smelting treatment and refining charges fell to historic lows, with some turning negative, meaning smelters were effectively paying miners for the privilege of processing their ore. At these margins, private capital does not build smelters. Policy uncertainty compounds the problem: analysts at Fastmarkets noted that confidence in the stability of tariff policies had eroded investor sentiment for new smelter development. The CSIS, in an October 2025 analysis, observed that the economics of developing new U.S. smelters simply did not add up, even with the tariff framework nominally intended to improve them.
The distribution of gains and losses under the current framework is not random. Commodity traders who repositioned early and physical arbitrageurs who redirected copper to COMEX warehouses extracted substantial profits from the spread between U.S. and global prices. At its widest, the COMEX-LME premium reached approximately $2,600 per tonne in July 2025, representing enormous windfall for those who had positioned copper in U.S. storage ahead of the tariff announcement.
The losses fall elsewhere. European and Asian manufacturers, who depend on copper as an input for electrical systems, wiring harnesses, construction materials, and renewable energy infrastructure, faced record regional premiums as the tariff pull redirected available supply toward U.S. warehouses. Supply Chain Magazine reported that COMEX warehouses held roughly half of all global exchange stocks while London and Shanghai inventories fell more than 55% since August 2025. For wire and cable manufacturers in particular, whose copper input costs are directly indexed to exchange prices, the COMEX-LME spread created deep uncertainty in how to price or hedge contracts, driving higher costs into finished products. Manthey at ING warned that higher copper costs were already pressuring margins in energy-intensive industries.
U.S. manufacturers are not immune. While the refined cathode exemption protects some downstream producers from direct tariff costs, the artificial elevation of COMEX prices relative to global benchmarks means that U.S. industrial buyers also pay a premium above what global supply fundamentals alone would justify. The policy inflates prices for American manufacturers while directing the arbitrage windfall to traders rather than producers.
The June 30, 2026, review is now the market's focal point. The Secretary of Commerce is required to report to the President on domestic copper markets, including refining capacity and the market for refined copper, to determine whether a phased duty on refined copper of 15% starting January 2027 and 30% starting January 2028 is warranted. The market is already pricing this risk. ING's Warren Patterson and Ewa Manthey noted in February 2026 that the threat of a 15% tariff hike on refined copper, under review in June, continues to support the COMEX-LME arbitrage even as the refined exemption nominally holds.
If refined copper tariffs are imposed, the global distribution of copper would shift further into U.S. warehouses, tightening already thin availability in Europe and Asia during a period of structural deficit. Manthey noted that material already moved into the U.S. is unlikely to be released back into the global system, because sector-specific tariffs remain in place and trade policy remains unpredictable.
The copper market's fundamental problem, its long-term supply gap driven by underinvestment in mining and processing infrastructure, cannot be solved by redirecting existing refin…