US car shares have come under particular pressure today as many of their cars and car parts are made in Mexico.
Fiat Chrysler is down more than 5%.
General Motors is down more than 4%.
Ford is down more than 3%.
All three companies depend on Mexico for cars and parts.
GM imports almost a third of its car parts from Mexico and Fiat Chrysler almost a quarter.
GM also sources 41% of its Silverado trucks from Mexico - it sells around 580,000 of those a year.