US stocks end a choppy day mixed. Intel warns of chip sales licenses. Trump calls for lower rates. UnitedHealth posts weak earnings.

U.S. stocks fell Wednesday after Nvidia warned new restrictions on exports to China will chisel billions of dollars off its results, while companies around the world said President Donald Trump’s trade war is clouding forecasts for how they and the economy will do this year.

The Fed chair's afternoon comments sparked further selling in stocks, which had already been under pressure from a sharp drop in shares of Nvidia and other chipmakers.