A pair of new surveys, one by consultancy KPMG and the other by advisers Grant Thornton, show a new wave of mergers and acquisitions activity is beginning that could build through this year and beyond if the economy continues its slow rebound as expected.

Global M&A activity in 2010 totaled $2.4 trillion, up 23% from 2009, according to Thomson Reuters. Most deals in 2010 were smaller, although four topped $20 billion in size. Private equity deals also increased last year, and buyout deals were up 84%, to almost $200 billion. The expectation is that the numbers will be even higher for 2011.

But this uptick appears to be M&A with a difference.

The last M&A boom involved a lot of stripping costs from acquired firms, says Dan Tiemann, leader of KPMG’s transaction and restructuring group. “This time it’s about winners, who have made it through the financial crisis and the recession, saying, ‘OK, what parts of our operation are we going to grow?’” Tiemann says. “It’s about geographical and service-line expansion. Companies are looking at filling out the top line, at revenue growth.”

Steve Brady, national managing partner of transaction advisory services at Grant Thornton, agrees. “This increase in M&A is absolutely a question of expanding top-line growth,” Brady says. “The cost-cutting has been taken care of over the past few years. This is about expanding into markets that companies feel they have been underrepresented in.”

Brady notes that a good deal of the activity consists of acquisitions by U.S. companies of businesses in Europe and South America–especially Brazil.

U.S. companies have piled up a reported $2 trillion in cash on their balance sheets. But Tiemann says that for the most part, they’re not using that cash to fund their acquisitions. “The fuel for the M&A we’re seeing is investors seeking returns, so money is flowing into the higher-yield bond market,” he says. “It’s not so much that companies are using their stockpiles of cash.”

This could suggest that companies remain a bit skittish about the future direction of the economy, which could explain why even as M&A activity picks up, hiring–or re-hiring–remains sluggish.