The S&P 500 inched forward on relatively light volume on Wednesday, with investors adding selectively to winning positions, this time in technology, avoiding large bets ahead of earnings.

The Dow Jones industrial average <.DJI> gained 32.85 points, or 0.27 percent, to end unofficially at 12,426.75. The Standard & Poor's 500 Index <.SPX> rose 2.91 points, or 0.22 percent, to 1,335.54. The Nasdaq Composite Index <.IXIC> added 8.63 points, or 0.31 percent, to 2,799.82.

(Reporting by Chuck Mikolajczak; Editing by Jan Paschal)