U.S. stocks opened modestly lower on Tuesday as the stunning summer rally appeared set to pause after the S&P 500 closed at its highest level in three months a day earlier. The S&P 500 /zigman2/quotes/210599714/realtime SPX -2.11% shed 3 points, or 0.1%, to 4,292. The Dow Jones Industrial Average gained 30 points, or 0.1%, to 33,958, as the blue-chip average was bolstered by strong earnings from Walmart Inc. /zigman2/quotes/207374728/composite WMT -0.61% . The Nasdaq Composite declined 30, 0.2%, 13,097. Stocks have rallied sharply since hitting their lows of the year in June. The S&P was up more than 17% through Monday from its mid-June low, but remains down 10.4% from its Jan. 3 record close.