President Donald Trump signed executive actions on Wednesday imposing a 50% tariff on Brazil, a 50% tariff on certain copper products and suspending a tax perk for all countries that allowed cheap packages to fly into the US duty-free.

US copper prices plunged by as much as 20% after President Trump said he would impose 50% tariffs on imports of semi-finished copper products, but not on the raw material itself.

Copper traded in New York dropped about 18 per cent to $4.60 a pound in tumultuous trading after the president’s announcement. Futures had surged to a record high of nearly $6 earlier this month when Trump announced the copper tariffs, but declined to provide specific details on which products they would apply to.