Stocks rose 1 percent at the open on Thursday after the European Central Bank surprised markets by cutting interest rates and as a Greek referendum on its euro zone membership was put into question.
The Dow Jones industrial average gained 136.00 points, or 1.15 percent, to 11,972.04. The Standard & Poor's 500 Index rose 12.66 points, or 1.02 percent, to 1,250.56. The Nasdaq Composite Index climbed 23.93 points, or 0.91 percent, to 2,663.91.
(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)