Futures tracking aluminum and steel prices in the U.S. surged after President Donald Trump said he will double tariffs on the metals this week.

Contracts linked to the prices that manufacturers pay to get aluminum delivered to the U.S. Midwest jumped 54% to the highest since 2013 on the Comex exchange in New York on Monday — offering an early glimpse of the much higher costs for American factories, with import levies set to rise to 50% from Wednesday.

Aluminum used in everything from beer cans to engine blocks and window frames was priced at a premium of 58 cents a pound, or about $1,280 a ton, in the Midwest over benchmark London contracts. That suggests U.S. buyers could end up paying about 50% more than international competitors to get hold of the metal.

Trump hopes the increased levies will protect margins for domestic mills and spur investment in new production capacity, and shares of U.S. steel and aluminum makers surged in after-hours trading after the announcement on Friday. But construction companies have warned that levies on steel and aluminum — which Trump had already raised from 10% to 25% — will increase the cost of critical building materials.

Comex steel futures were up more than 8% before paring some of the gains on Monday — and while both contracts are relatively illiquid — the moves indicate that the commercial burden of the tariffs will weigh most heavily on the U.S. aluminum market. More than 80% of the aluminum used in the U.S. is supplied via imports, while less than 20% of the country’s steel is sourced from overseas, according to Morgan Stanley.

“We expect prices to rise — the U.S. does not have enough domestic capacity of either,” analysts at Citigroup Inc. said in an emailed note. For aluminum in particular, the tariffs have “mostly just functioned as a tax on consumers thus far.”

Benchmark aluminum contracts on the London Metal Exchange traded 0.9% higher to settle at $2,466 a ton at 5:50 p.m. local time. Copper was up 1.2% in London and nearly 4% higher on Comex, as analysts said the heightened levies make it more likely that Trump will follow through with plans to place tariffs on the metal.

“The market also appears to be pricing a higher likelihood of copper tariffs, with COMEX outperforming LME,” Morgan Stanley analysts led by Amy Gower said in an emailed note, noting that U.S. buyers have been front-loading imports ahead of potential tariffs. “For now, the COMEX premium is likely to continue pulling material to the U.S., drawing down ex-U.S. inventories and keeping ex-U.S. markets tight.”

(With assistance from Jack Farchy and Yvonne Yue Li.)

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