Stocks slipped, but were trading tight Tuesday amid mixed economic data. The Nasdaq briefly hit a new high early before pulling back to a 0.2% loss. The S&P 500 fell 0.1% and the Dow Jones industrial average dipped a fraction. Volume was tracking mixed in the stock market today, narrowly higher on the Nasdaq and lower on the NYSE. From the Dow, UnitedHealth Group (UNH) posted the best gain, up close to 2% in above-average trade.