For the first time, global corporate dealmaking topped $5 trillion this year as companies paid dearly for growth in a slow economy.

The total represented a 37 percent increase from 2014, according to financial data firm Dealogic. That was thanks to a large number of megadeals worth $10 billion or more, including two in pharmaceuticals and beer, worth more than $100 billion.

The $65.59 billion merger announced this month between Dow Chemical Co. and Wilmington's DuPont Co., among the top 10 globally, accounted for more than half the $113.4 billion worth of deals this year involving Philadelphia-area companies, data from Bloomberg L.P. showed.

The DuPont deal skewed the numbers for the Philadelphia region far above the 2014 area total of $17.8 billion.

Even so, the number of $1 billion-plus deals in the region increased to 11 in 2015, including Carl Icahn's down-to-the-wire acquisition this week of Pep Boys. That activity is up from four in 2014, and the overall number of deals, including those with no published value, surged to 344 from 249, according to an Inquirer analysis of Bloomberg data through Tuesday.

The combination of abundant cash in the coffers of corporations and other buyers, relatively slow economic growth, and a paucity of high-quality companies to buy has driven up prices, experts said.

"It's a tough market for buyers these days. There's a lot of competition," said David Denious, a partner in Drinker Biddle & Reath's corporate and securities practice group.

Experts were mixed on whether next year would bring continued high times in the mergers-and-acquisitions world.

Michael McAleer, a partner in the Philadelphia office of KPMG L.L.P., said his firm's clients reported in a recent survey that they expect another big year.

"They expect it to be strong again in '16. They are telling us they have lots of cash. They have continued ability to get debt to finance deals," he said.

Others said rising interest rates will take some of the frothiness out of prices for buyers, such as private equity firms, which rely heavily on debt.

"It will absolutely create some friction," said Michael DiPiano, managing general partner of NewSpring Capital, a Radnor private equity firm, and president of the Association for Corporate Growth's Philadelphia chapter, a networking group for dealmakers.

As a seller, it was a banner year for NewSpring, with more sales of companies than any other year since its founding in 1999, DiPiano said. He said he could not disclose individual prices, but said the overall value of the firm's sales was around $250 million.

Locally, NewSpring sold Internet Pipeline, Precyse Solutions, and RightCare Solutions, he said.

On the buying side, NewSpring encountered some astonishing valuations of companies, DiPiano said. For example, a company that sells software for casual-dining restaurants was valued at $225 million in the fall even though it has just $7.5 million in revenue. That means sales would have to grow dramatically for an investor to get the level of return that private equity expects.

Another investor got that deal, DiPiano said.

"We couldn't make the math work under any circumstances," he said.

Bharat Ramprasad, an investment banker in the Philadelphia office of Stifel Financial Corp., said the market has been as good as he's seen it in his 13 years helping to sell companies that are typically worth $15 million to $300 million.

"I don't see necessarily irrational behavior from buyers, but I see aggressive behavior from buyers," Ramprasad said.

"They are stretching to what they feel is the maximum they can stretch for in many instances because they want the growth and they are struggling to get it by other means."

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