Stocks faced an onslaught of late selling Tuesday, giving up some gains to close modestly higher. The Nasdaq closed atop the heap with a 0.4% gain after being up as much as 0.9% earlier. The S&P 500 and the Dow gained 0.2% and 0.1%, respectively. The NYSE composite kept a toehold in positive territory. Volume rose across the board. But much of the trading took place as the market slid, a negative sign for the market. Normally, higher volume on a