Stocks finished mixed Tuesday, with the Nasdaq leading the other indexes back after a weak open as investors fretted over bad markets overnight in Asia and Europe. The Nasdaq rose 0.5%. The S&P 500 retreated slightly, and the Dow Jones industrial average lost 0.3%. Volume was heavier on both exchanges. In the stock market today among IBD 50 stocks, 35 were up and 15 were down. The best performer was chipmaker Cavium (CAVM), up nearly 6%.