A month-long rally on Wall Street appears to be sputtering, as stocks slipped on Thursday in what investors called a possible warning of weakness ahead.

Based on the latest available data, the Dow Jones industrial average <.DJI> was down 20.97 points, or 0.16 percent, at 12,735.99. The Standard & Poor's 500 Index <.SPX> was down 7.53 points, or 0.57 percent, at 1,318.52. The Nasdaq Composite Index <.IXIC> was down 12.50 points, or 0.44 percent, at 2,805.81.

(Reporting By Caroline Valetkevitch; Editing by Kenneth Barry)