Stocks battled back from morning losses to end narrowly mixed Tuesday. The Nasdaq cut a 0.9% deficit to 0.2%, while the S&P 500 bounced back from a 0.3% loss to end with a fractional gain. Elsewhere, the Dow Jones industrial average was fractionally lower. Volume rose on both major exchanges in the stock market today, according to preliminary data. In stocks, Southwest Airlines (LUV) slumped 4% for its sixth straight loss.