U.S. stocks opened higher Monday, propelled by a flurry of merger developments in the U.S. and overseas, including a hostile $9.2 billion bid from Canada's Barrick Gold for U.S. miner Placer Gold. The Dow Jones Industrial Average last was up almost 38 points at 10,440. The S&P 500 was up 4 points at 1,202 and the Nasdaq Composite was up 8 points at 2,098.