US President Donald Trump’s first wave of copper tariffs will hit imports valued at more than $15 billion last year, highlighting the potential inflationary impact on American buyers.

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.

In a flurry of trade news on Wednesday, Trump imposed new rates on copper imports and ended the de minimis exemption.