Stocks turned mixed early Monday afternoon as investors awaited a speech by Federal Reserve Chairman Ben Bernanke. Bernanke is expected to discuss the U.S. economic outlook later Monday in a speech at the University of Michigan. The Nasdaq fell 0.5% and the S&P 500 lost 0.3%, while the Dow Jones industrial average was up a fraction. Volume was 3% higher on the Nasdaq and 10% lower on the NYSE compared with the same time Friday. Apple (AAPL) fell