Comex copper plunged over 19% in minutes after Trump excluded refined metal from his planned import tariff - the largest intraday fall on record. Prices later pared some of the losses.

The US copper market suffered its largest intra-day fall on record after President Donald Trump shocked traders by exempting the most widely imported form of copper from his planned tariffs.

The president stopped short of putting a 50 percent tariff on refined copper, as he had threatened earlier this year. The market reaction was swift anyway and prices tumbled.