U.S. stocks ended the trading day sharply lower after President Trump escalated trade war rhetoric Friday, tweeting that he had "hereby ordered" U.S. companies "to immediately start looking for an alternative to China." The Dow Jones Industrial Average DJIA, +1.33% fell 614 points, or 2.6% to 25,633, the S&P 500 index SPX, +1.59% lost about 75 points, or2.6% to 2,848 and the Nasdaq Composite COMP, +2.26% lost 240 points, or 3% to close around 7,751. Trump's tweets were in apparent response to China announcing new tariffs of 5% and 10% on $75 billion in U.S. imports in retaliation for the Trump Administration plans to institute a new round of tariffs on $300 billion in Chinese imports, starting Sept. 1. Meanwhile, Federal Reserve Chairman Jay Powell gave a speech at the Fed's annual symposium in Jackson Hole, Wyo. in which he said "the U.S. economy has continued to perform well overall," but appeared to leave the door open for a possible quarter-point rate cut at its next meeting in September.