The U.S. dollar surged against the yen on Monday, topping the 125 yen line for the first time since August 2015, after the Bank of Japan announced an emergency bond-buying operation, while the Nikkei stock index ended lower, snapping a nine-day winning streak.The dollar rose sharply from the lower 122 yen range in the morning after the BOJ's operation increased expectations of a widening interest rate gap between the United States and Japan.The U.S. currency eclipsed the 125 yen mark in the evening. At 6 p.m., the dollar fetched 124.68-69 yen compared with 122.05-15 yen in New York and 121.…READ FULL ARTICLE