President Donald Trump has proposed a 50% tariff on all copper brought into the United States, a levy far higher than industry participants had anticipated. Although the White House has yet to publish final guidance on product coverage or possible exemptions, traders have been told the duty could be applied from 1 August. The announcement has upended the market. New-York-traded Comex copper futures have climbed 38% since January, widening an already-large premium over London Metal Exchange prices, which are up 10% over the same period. Importers rushed metal into the country ahead of the deadline, pushing stocks in Comex-approved warehouses to their highest level in seven years. US buyers are now slashing purchases and leaning on inventories. RM-Metals, a distributor in New Jersey, cut incoming volumes by about 25% and cancelled pending orders where possible, citing customers’ reluctance to shoulder the prospective duty. Houston-based Aviva Metals has suspended some transactions until the administration clarifies whether semi-finished products such as brass and bronze will be covered. Manufacturers from Texas to New Jersey say the uncertainty is already dampening demand for copper used in construction, appliances and data-centre wiring. While some economists warn the tariff could add to inflationary pressures later in the year, major lenders including JPMorgan and Citigroup reported robust consumer spending and borrowing in their latest results, suggesting broader economic activity remains resilient for now.