President Donald Trump repeated his attacks Monday against the chair of the Federal Reserve, demanding that the central bank lower its key interest rate to boost the economy. Trump called Powell “a major loser” and said that energy and grocery prices are “substantially lower” and “there is virtually No Inflation.” Trump's comments drove the stock market and the dollar lower as investors in the U.S. and overseas grow increasingly wary about the economic standing of the U.S. On Friday, a top White House adviser said the administration is studying whether it can fire Powell, a move that would undermine the Fed's independence and likely send shock waves through global financial markets.