On Wall Street, the Dow Jones plummeted 7% at midday, triggering an automatic halt to trading for the fourth time in the last two weeks. The market crash has wiped out nearly all stock market gains since President Trump took office in early 2017. On Wednesday, all big three U.S. auto companies — Ford, General Motors and Fiat Chrysler — decided to halt production for at least two weeks, under pressure by the United Auto Workers union to close plants for safety reasons. The closures came after a worker at a Ford plant in Dearborn, Michigan, tested positive for COVID-19. About 150,000 factory workers will be idled; under a union agreement, many will receive supplemental pay along with state unemployment benefits. Meanwhile, Hyundai halted production at its plant in Montgomery, Alabama, after a worker tested positive.