A Bloomberg agriculture index fell to the lowest since at least 1991, while a gauge of global mining stocks headed for the biggest decline in almost two years. Industrial metals fell, with aluminum, nickel and zinc all giving up more than 2 percent. Freeport-McMoRan Inc., the world’s largest publicly traded copper producer, and Alcoa Corp., the biggest U.S. aluminum make, lost more than 3 percent. First Quantum Minerals Ltd. dropped more than 4 percent.
The spat is upending commodities markets that as recently as last month had climbed to an almost three-year high on signs of a strengthening global economy. China, the biggest raw-materials consumer and a key destination for some U.S. farm goods, vowed to retaliate "forcefully" against Trump’s threatened tariffs.