Major indices on Wall Street opened lower on Wednesday as investors awaited the Federal Reserve's decision regarding interest rates later in the day. Meanwhile, shares of UnitedHealth Group fell after the company warned of rising medical costs. The Dow Jones Industrial Average dropped 167.42 points or 0.49 percent to 34,044.70 points. The S&P 500 index decreased by 2.72 points or 0.06 percent to 4,366.29 points, while the Nasdaq Composite fell 2.76 points or 0.02 percent to 13,570.56 points.