NEW YORK (AP) — U.S. stocks ended a choppy day higher after the Federal Reserve left its main interest rate alone, as was widely expected, but also warned about rising risks for the U.S. economy. The S&P 500 rose 0.4% Wednesday. The index is coming off a two-day losing streak that had snapped its nine-day winning run. The Dow Jones Industrial Average rose 0.7%, and the Nasdaq composite added 0.3%. Fed Chair Jerome Powell said the central bank has time to wait before making any potential moves on rates, but he warned that sustained tariffs could both weaken the economy…