Stocks firmed up Thursday afternoon, with all of the major indexes back in positive territory. The S&P 500 and the Dow Jones industrial average were up 0.4% and 0.3% respectively. Meanwhile, the Nasdaq turned fractionally higher after bouncing back from a 0.2% loss. Big caps such as Amazon.com (AMZN), Google (GOOG) and Priceline.com (PCLN) were lower, but there was some strength among chip issues. ARM Holdings (ARMH) and Cirrus Logic (CRUS) rose