U.S. stocks ended mixed Tuesday, with technology shares falling. The Dow Jones industrial average rose 51.74, or 0.2 percent, to 24,579.96. The broader Standard & Poor's 500 index fell 3.85, or 0.15 percent, to 2,640. The technology-heavy Nasdaq composite index fell 57.40, or 0.8 percent, to 7,028.29.