Shares of Freeport-McMoRan Inc. tumbled on Tuesday and were on track for their biggest one-day drop in more than two years after the company reported first-quarter results that came in below forecasts. The stock sank 13.3%, which is poised to be its worst session since January 2016. Freeport was the biggest percentage decliner among S&P 500 components. More than 32 million shares of the mining company exchanged hands, more than twice its 30-day average of 14.5 million. The stock is down about 14% thus far this year, although it remains up by more than 33% over the past 12 months. The Dow Jones Industrial Average fell 0.6% while the S&P 500 was down 0.4% and the Nasdaq Composite Index fell 0.7%.