U.S. stocks fell modestly Thursday, with the Standard & Poor's 500 and Nasdaq indexes hitting new intraday highs before declining. The Dow Jones industrial average fell 128.11, or 0.4 percent, to 29,423.31. The broader Standard & Poor's 500 index fell 5.51, or 0.2 percent, to 3,373.94. The technology-heavy Nasdaq composite index fell 13.99, or 0.1 percent, to 9,711.97.