Copper Market in Turmoil as Trump Touts 50% Tariff on US Imports

President Donald Trump sowed fresh chaos in metals markets by indicating the US would implement a higher-than-expected 50% tariff on copper imports, spurring a record spike in New York futures and a drop in the global benchmark.

The plan, announced in an apparently off-the-cuff comment to reporters, marks the latest twist in a tumultuous period for industrial commodities, as the US leader aims to encourage more mining and smelting at home. He’s already raised fees on steel and aluminum imports, while probes into flows of multiple other metals are in train.

Since February, when Trump ...