
Shares of U.S. automakers fall after President Donald Trump threatens new tariffs
Trump threatens to "substantially increase" tariffs on cars coming into U.S on April 2 "if other egregious, long-time tariffs are not likewise dropped by Canada"
Ford Motor F.N falls 3.2%, General Motors GM.N down 3.7%
Tesla TSLA.O pares premarket gains in choppy trading, last up 0.4%
S&P 500 automobile index .SPLRCAUTO drops 1%
Trump also says he will doubles planned tariffs on all steel and aluminum products coming into U.S. from Canada
Including day's moves, S&P 500 auto index has dropped ~42% this year