Stocks eked out gains after hovering around the flatline for much of the session on Monday, as investors remained cautious, but the Nasdaq rallied, thanks to a strong performance in Internet stocks.
The Dow Jones Industrial Average ended the day unofficially 20 points higher, the S&P 500 rose 7 points and the tech-heavy Nasdaq added 35 points.
The day started sluggishly, following the first back-to-back weekly losses since January for the S&P 500, as investors pulled back amid recent mixed economic data and merger activity took center stage.
Investors have flocked to "safe haven" assets like U.S.Treasury bonds, and out of stocks, on concerns including when the Federal Reserve might start raising interest rates, whether the European Central Bank will announce further monetary stimulus, and the turmoil in Ukraine.
Equities have come under selling pressure in recent days, with consecutive weekly declines for the S&P for the first time since January. Small-cap stocks, often seen as the first beneficiary of growth, have tumbled with the Russell 2000 index briefly dipping into correction territory last week.
Merger and acquisition news remained in focus. Pfizer shares climbed after British rival AstraZeneca rejected a sweetened takeover bid. Meanwhile, shares of AT&T slipped after the telecom company launched a $48.5 billion for satellite TV operator DirecTV on Sunday.
General Electric traded flat despite reports that Germany's Siemens could make a rival bid for Alstom's power business as early as this week. General Electric has already submitted a 12.35 billion euro ($16.9 billion) bid, but Alstom has opened its books to Siemens sunder strong political pressure from the French government.
Campbell Soup dropped over 2 percent after reporting weaker-than-expected quarterly sales and lowered its full-year revenue growth forecast.