"The US equity markets are higher in early action as traders continue to deal with lingering Middle East uneasiness and some global M&A reports," said analysts at Charles Schwab.

Among the deals in play were Blackstone Group's move to buy some US assets of Australia's Centro Properties Group for $9.4 billion and Australia's Equinox Minerals' offer for Canada's Lundin Mining.

JPMorgan Chase was also rumored to be seeking a stake in social media site Twitter.

The Dow Jones Industrial Average added 95.78 points (0.79 percent) at 12,226.41 at 1530 GMT and the tech-rich Nasdaq rose 13.81 points (0.50 percent) to 2,794.86.

The broad-market S&P 500 index advanced 8.67 points (0.66 percent) to 1,328.55.

Among the Dow's top winners was 3M Company. Its share price was up 1.5 percent.

United Continental stocks were up over two percent and Hewlett-Packard rose 1.9 percent.

Economic news appeared to have little impact on the markets.

Pending home sales for January were down 2.8 percent, a smaller drop than expected.

US consumers tightened their wallets in January after the holiday shopping season despite a sharp rise in incomes, official data showed.

The Commerce Department reported consumer spending edged up a seasonally adjusted 0.2 percent in January, the weakest pace since June.

Bonds rose. The yield on the 10-year Treasury bond fell to 3.414 percent from 3.435 percent late Friday while the 30-year bond fell to 4.501 percent from 4.516 percent a session earlier.

Bond prices and yields move in opposite directions.