U.S. stocks were mostly lower Monday, with the Dow industrials declining for a third consecutive session. The Dow Jones industrial average fell 165.89, or 0.6 percent, to 29,232.19. The Standard & Poor's 500 index fell 9.87, or 0.3 percent, to 3,370.29. The technology-heavy Nasdaq composite index was virtually unchanged, rising 1.57 to 9,732.74.