Copper returns to London warehouses but most is not available for market delivery

For 42 straight trading days the copper piles in London Metal Exchange warehouses shrank, the longest such run since 2014. Then, over two sessions on August 14 and 17, stocks jumped by a combined 18,600 tonnes to 233,600 tonnes, including a single-day inflow of 17,500 tonnes, according to Shanghai Metals Market as quoted by Mining.com.au on August 19.

On its face the drain is over and the market is refilling. That reading is wrong: what returned is mostly metal locked inside the exchange's own ledger, unavailable to anyone else, while the pool of freely deliverable copper sits at levels that historically precede a delivery squeeze.

The contradiction lives in the warrant split, which most headlines ignore. LME Insight reported on August 21 that total LME copper stock hit 402,625 tonnes on April 14 this year, then fell almost half to 204,975 tonnes by August 13.

The more revealing number, as LME Insight described in the same August 21 report, is open tonnage: metal genuinely available for delivery stood at 339,125 tonnes on May 11 and had collapsed to about 94,875 tonnes by August 13—a roughly 72 percent drop in three months. Cancelled warrants, meaning metal booked to leave but still physically present, made up more than half the remaining pile.

A headline "refill" counts cancelled metal too. The buyers who cancelled those warrants have no intention of leaving it in Busan or Kaohsiung.

Two pulls drained the same pool at once. American buyers shipped refined copper into the United States at the fastest pace in at least twelve years during July, positioning ahead of a possible tariff. At end-July, COMEX-approved warehouses held a record 700,000 short tons, about 635,000 metric tonnes, based on CME Group data cited by LME Insight on August 21.

At the same time, Chinese smelters short on feedstock pulled cathode out of LME sheds in Taiwan and South Korea toward Shanghai. The London system became the balancing tank for two regional drains. Societe Generale's analysis, published via MetalsCost on August 15, now models the gap between New York and London copper prices as a live odds board. They estimate roughly a 14.6 percent chance of a 15 percent US tariff on refined copper by January 2027, and a 37 percent chance of a 30 percent duty by January 2028.

Two drains, one pool

The trigger this month looked like Kinshasa, as the Democratic Republic of Congo banned exports of copper and cobalt concentrate, and MetalsCost reported on August 15 that cash copper spiked to an all-time high of 14,453.60 dollars a tonne on August 11. But most Congolese copper is already smelted inside the country and waivers are available, so the ban is noise; the pressure underneath is Washington's unresolved Section 232 review.

LME Insight explained on August 11 that this review keeps paying anyone who moves metal into America before the deadline and punishes anyone who waits. The tariff has not been imposed, but its possibility alone moved hundreds of thousands of tonnes across oceans.

The price structure shows who feels it. The premium of immediate-delivery copper over three-month copper widened from 44.50 dollars to 416.50 dollars a tonne in a single week in mid-August, which LME Insight reported on August 17, and touched 434 dollars—a five-year high, as noted by MetalsCost on August 15. That is the sound of traders with short positions for imminent delivery dates scrambling for metal that is not for sale.

The LME's own rulebook, according to LME Insight's August 11 report, concedes the danger. Once open warrants fall below 80,000 tonnes, the exchange's guidance letting shorts borrow their way out no longer applies, and the market enters territory where position stress sets the price.

October 2021

In October 2021, a handful of holders cornered nearby LME prompt dates and the exchange intervened directly in the copper market, forcing adjustments to protect shorts; the widest one-month spread since then is exactly what reappeared this August, as MetalsCost noted on August 15. When open metal gets scarce relative to outstanding obligations, price stops being an opinion about demand and becomes a ransom note.

What differs this time is direction. The 2021 squeeze happened inside a broadly balanced physical market, while today's runs come on two fronts at once, with China's own exchange stocks falling even as America's overflow into rented sheds in Cartersville, Georgia and Mobile, Alabama, where COMEX approved new capacity this summer, according to CME approvals cited by LME Insight on August 21.

Visible copper across the LME, COMEX and Shanghai exchanges reached 962,000 tonnes this August, nearly double the 486,000 tonnes a year earlier; Mining Reporters reported that figure on August 18. If the world holds twice the metal it did last summer, talk of scarcity is theater, and the dip in New York prices as London stocks rebuilt suggests exactly that.

This is a genuine argument. The metal exists. But geography decides who can deliver it, and a wire rod mill in Taicang cannot draw on a warehouse in Detroit no matter what the global total says. Abundance in the wrong harbor is scarcity with extra steps.

First, whoever sold forward copper they must deliver in London pays. Fabricators and merchants hedging orders with short LME positions buy back at premiums measured in hundreds of dollars a tonne, costs that land in wiring harnesses, transformers and construction quotes within a quarter.

Second, the arbitrage feeds on the uncertainty it creates. Every week Washington delays the Section 232 decision, freight and financing firms earn another round trip moving cathode into America, and London gets emptier.

Third, if open warrants do breach that 80,000-tonne line before the tariff question resolves, the LME faces a choice between letting a squeeze run, as it did in 2021, or intervening again, and intervention would tell every trader watching that the exchange's warehouse network no longer matches its contract book.

Continued cancellations eating into open tonnage after the mid-August inflow, pushing freely available warrants below 80,000 tonnes, alongside a cash-to-three-month spread holding above 300 dollars, would confirm this read. What breaks it: Washington announcing a clear refined-copper tariff decision either way, which collapses the arbitrage, releases cancelled metal back onto the market and turns the refill real, or a hard landing in Chinese demand that ends the eastern pull.

End where the tonnage sits. The copper never vanished; it is stacked in Georgia and Alabama sheds approved this summer because a government memo was worth more than a delivery order. The people who pay are the manufacturers who assumed London meant available.

In a market split by a border tax nobody has signed, the warehouse number everyone watches is the least honest one on the tape.