Stocks coasted to nice gains Friday in volume that suggested not everybody was pedaling. The S&P 500 and the Nasdaq rose 0.5% and 0.4%, respectively. The Dow Jones industrial average popped 0.6%. The IBD 50 added 0.7%. Volume sagged on both major exchanges. Yet something could be about to change. The Nasdaq is waging a quiet battle around the 5,000 level, an area where it encountered resistance twice before.