NEW YORK, May 15 (Reuters) - U.S. stocks fell on Thursday, giving the Dow its worst decline in a month, as small-cap shares extended their retreat and Wal-Mart's results disappointed.
The Dow Jones industrial average fell 167.16 points or 1.01 percent, to end unofficially at 16,446.81. The S&P 500 lost 17.68 points or 0.94 percent, to finish unofficially at 1,870.85. The Nasdaq Composite dropped 31.33 points or 0.76 percent, to close unofficially at 4,069.29. (Reporting by Chuck Mikolajczak; Editing by Jan Paschal)