The stock market got off on the wrong foot to start 2015, blowing an early lead to finish mostly down on the first trading day of the year. But stocks finished off their worst levels of the day, and the Dow Jones industrial average managed a 0.1% gain. The Nasdaq fell 0.2% and the S&P 500 lost a smidgen. Preliminary data showed NYSE and Nasdaq volume coming in slightly higher than Wednesday’s levels.