NEW YORK (AP) — U.S. stocks are drifting in mixed trading on Wednesday after the Federal Reserve left its main interest alone, as was widely expected, but also warned about rising risks for the U.S. economy. The S&P 500 was 0.1% lower in late trading, coming off a two-day losing streak that had snapped its nine-day winning run. The Dow Jones Industrial Average was up 160 points, or 0.4%, with roughly 20 minutes remaining in trading, and the Nasdaq composite was 0.4% lower. Indexes had been modestly higher earlier in the morning, with the Dow briefly up 400 points, on…