U.S. stocks ended mixed in a volatile session Monday. The Dow Jones industrial average fell 53.22, or 0.2 percent, to 25,053.11. The broader Standard & Poor's 500 index was little changed, rising 1.92 to 2,709.80. The technology-heavy Nasdaq composite index rose 9.71, or 0.1 percent, to 7,307.90.