NEW YORK — U.S. stocks rose, briefly sending the Standard & Poor’s 500 Index above 2,000 for the first time ever, as corporate dealmaking and prospects for economic stimulus in Europe bolstered confidence in the bull market.

The S&P 500 rallied 0.5 percent to 1,997.92 at 4 p.m. Monday in New York, paring gains in the afternoon after holding above 2,000 for less than two hours and reaching a record 2,001.95. The Dow Jones Industrial Average increased 75.65 points, or 0.4 percent, to 17,076.87. About 4.3 billion shares changed hands in the U.S. on Monday, 23 percent below the three-month average.

“This number, 2,000, is a pretty significant number from psychological and financial points,” Joe Bell, senior equity analyst at Cincinnati-based Schaeffer’s Investment Research, said in a phone interview. “Perhaps we might reach a little bit overbought status, and it looks like the index is going to take a breather there.”

Merger and acquisition activity led to some of the biggest moves in the market on Monday. Burger King added 20 percent after saying it’s in talks to buy Tim Hortons and move its headquarters to Canada. InterMune surged 35 percent after Roche purchased the biotechnology company for $8.3 billion. Morgan Stanley climbed to the highest since 2009 and JPMorgan Chase and Goldman Sachs climbed more than 1.3 percent.

The S&P 500 has recovered almost 100 points since its low during trading on Aug. 7, climbing on nine of 12 days to erase the 3.9 percent drop that began on July 24.