Wall Street closed lower Wednesday but indexes posted monthly gains during May.
The Dow fell 20 points to 21,008 and the S&P lost one point to 2,411.
The Nasdaq decreased four points to 6,198.
The indexes, however, ended the month in positive territory.
The Dow and the S&P gained 0.4 percent and 1 percent, respectively, while the Nasdaq increased 2.5 percent -- a seventh straight monthly gain and a first since 2013.