U.S. stocks ended April on a sour note with the S&P 500 falling 1.57% on the final trading day of the month, its worst single-day loss since January 31. Investors reeled after the government released a report showing employment costs rose 1.2% in the first quarter, its largest increase in a year and up 4.2% from a year ago. The increase signals renewed wage pressures and provides additional evidence that persistent inflation may force the Federal Reserve to keep interest rates higher for even longer than previously believed.