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.

The once-mighty premium U.S. copper enjoyed over the global benchmark slid on Thursday as markets clawed back months of gains in hours of frenzied trading after President Donald Trump surprised markets with pared-back tariffs.