
U.S.-listed shares of car makers lose ground ahead of President Donald Trump's planned announcement of tariffs on auto imports
Trump's press conference expected at 4 p.m. ET
Trump in the past has floated levels of 25% tariffs on auto imports
General Motors GM.N falls 1.5%, Ford F.N loses 1.1%, Tesla TSLA.O drops 5.6%
Toyota Motors' U.S. listing TM.N drops 1.8%, BMW BMWKY.PK loses 3.4%
S&P 500 automobile index .SPLRCAUTO has slumped over 30% year-to-date amid worries about tariffs and weakening demand