Stocks ended lower Thursday, giving up strong early gains in another whipsaw trading session. The Dow Jones Industrial Average DJIA, -0.02% lost around 7 points, or less than 0.1%, to close near 34,161, according to preliminary figures, after rising more than 600 points in earlier action. The S&P 500 SPX, -0.54% fell around 23 points, or 0.5%, to close near 4,327, while the Nasdaq Composite COMP, -1.40% dropped around 189 points, or 1.4%, finishing near 13,353.