U.S. stocks opened slightly higher on Wednesday as investors prepared for an expected interest-rate hike from the Federal Reserve in the afternoon. Higher oil prices, after days of declines, lifted energy shares. WTI futures for April delivery CLJ7, +1.61% rose 1.6%. The S&P 500 SPX, +0.16% rose 5 points, or 0.2%, at 2,370. The Nasdaq Composite COMP, +0.06% advanced 10 points, or 0.2% to 5,866. The Dow Jones Industrial Average DJIA, +0.15% gained 35 points or 0.2%, to 20,874 at the open.