The news added to worries about the outlook for U.S. earnings, with S&P 500 profits forecast to have dropped more than 4 percent in the third quarter compared with a year ago, according to Thomson Reuters data. Wal-Mart (WMT.N) sank 10 percent to $60.03 in its biggest one-day percentage decline in years and heaviest trading day since January 2009, after it forecast a drop of up to 12 percent in earnings per share in fiscal 2017. The day’s decline erased more than $20 billion off the retailer’s market value, and the stock was among the biggest drag on both the Dow and S&P 500.