U.S. stocks opened slightly lower as the market took a breather with the S&P 500 index near a record high, while low volume could make trading volatile and exaggerate moves.

The Dow Jones industrial average <.DJI> was down 23.46 points, or 0.17 percent, at 13,969.51. The Standard & Poor's 500 Index <.SPX> was down 1.99 points, or 0.13 percent, at 1,515.94. The Nasdaq Composite Index <.IXIC> was down 1.86 points, or 0.06 percent, at 3,192.01.

(Reporting By Angela Moon; Editing by Kenneth Barry)