Stocks rallied Wednesday on upbeat economic data and rising oil prices.
The Dow Jones industrial average closed the day up 92 points.
Gains were broad-based, but the energy sector was the strongest. The healthcare sector was the second-biggest gainer, on news that U.S. health regulators approved Arena Pharmaceuticals Inc's pill to treat obesity, the first weight-loss drug in 13 years.
Easing concerns about tepid economic growth, data showed demand for long-lasting U.S. manufactured goods rose more than expected in May.
In another report, signed contracts for home purchases jumped in May to the most in seven months, the latest sign of improvement in a sector that has been a drag on the economy.
But investors remained hesitant to make big bets ahead of the euro zone leaders' summit on Thursday. Few anticipate anything concrete to emerge from the two-day meeting after German Chancellor Angela Merkel said debt sharing, an idea backed by France, Italy and Spain, would not happen in her lifetime.
"We are in a market now, where in the absence of bad news, the market just goes higher and then with bad news, the gains are instantly erased," said Randy Frederick, managing director of active trading and derivatives at the brokerage Charles Schwab.
"I think building your position now [ahead of the EU summit] is pretty dangerous, without clearly hedging your portfolio."
With Spanish 10-year yields near the 7 percent level, the euro zone's fourth-largest economy appears set to be the next country to seek a bailout.
Some of Wall Street's top analysts published their research on Facebook, and most are cautiously optimistic.
A U.S. judge on Tuesday backed Apple's request to stop Samsung selling its Galaxy Tab 10.1 tablet in the United States, giving the iPhone maker a significant win in the global smartphone and tablet patent wars.
Google shares gained after reports the company will soon unveil a tablet co-branded with Taiwan's Asustek Computer and priced to compete with Amazon's Kindle Fire.
Reuters contributed to this report.