Demand for U.S. corporate bonds has surged after the Federal Reserve signaled that it’s done raising interest rates for now and eased investor concerns that rate hikes will choke off economic growth and crimp profits. High-yield bonds gained 5.3 percent this year through Feb. 6, the best start to a year since 2009, and saw the biggest fund inflows this week since July 2016. For investment-grade bond deals, investors this week put in six or eight times as many orders as there are securities for sale, about two or three times the usual levels of oversubscription.