U.S. stocks traded mostly lower at the opening bell on Wednesday as investors looked forward to the Federal Reserve’s policy update, where the central bank may acknowledge the improvement in economic data. The S&P 500 was up less than 0.1% to 4,188. The Dow Jones Industrial Average retreated 134 points, or 0.4%, to 33,851. The Nasdaq Composite slid 0.3% to 14,053. Still, investors expect the U.S. central bank to emphasize its commitment to its accommodative policies. Shares of Dow component Microsoft Corp. were down even after delivering earnings late Tuesday that easily topped Wall Street forecasts.

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