U.S. Stocks Struggle To Build On Gains As Oil Prices Slip

U.S. stocks opened flat Thursday, struggling to build on a three-day rally carried them to their highest levels of the year. Sliding oil prices weighed on the energy sector, while the tone of corporate earnings reports was mixed. The Dow Jones Industrial Average shed 23 points, or 0.1%, to 18,072. The S&P 500 rose 1 point, or less than 0.1%, to 2,102. The Nasdaq Composite was flat at 4,948. General Motors Co. and American Express Co. saw their shares rise after earnings surpassed expectations, while Verizon Communications Inc. reported soft results.