Stocks had a choppy session but found their footing late Monday and closed higher, spurred on by another round of merger news and lower oil prices.
The Dow Jones Industrial Average rose 42.30 points, or 0.34% to 12,318.62. The index had spent much of the day near the flat line, and earlier was down as much as 30 points.
Nineteen of the Dow's 30 components finished in the black, led by gains of 1.9% or more in Intel and Boeing.
Meanwhile, the S&P 500 ended up 3.75 points, or 0.27%, at 1406.60, and the Nasdaq Composite added 14.74 points, or 0.62%, to 2402.29.
Roughly 2.57 billion shares changed hands on the New York Stock Exchange. Advancers beat decliners by a 5-to-3 margin. Volume on the Nasdaq reached 1.60 billion shares, with winners outpacing losers 9 to 7.
Market subsector winners included the Amex Airline Index, which was higher by 1.3%. The Philadelphia Semiconductor Sector Index rose 0.9%, and the S&P Retail Index tacked on 0.5%.
Among losers, the Philadelphia Housing Sector Index fell 2.2%. The Amex Oil Index slid 0.4%, and the Philadelphia/KBW Bank Index dipped 0.1%.
"The market 'shake-up' of the past couple of weeks has done little to the top industry groups," said Paul Nolte, director of investments with Hinsdale Associates. "We expect there may be more declines ahead that are likely to force money from the top-performing sectors toward the bottom. It has happened repeatedly in the past, and we expect the future to at least rhyme."