Mergers and acquisitions pros are worried that Donald Trump may not be so great for the world of dealmaking. A key tenet of Trump's presidential campaign is his criticism of government officials for poor dealmaking, particularly when it comes to trade deals and military treaties. However, the corporate world's dealmakers believe a President Trump might hurt their own chances in the big money world of M&A. A recent survey of investment bankers, development professionals and private equity leaders showed that 62 percent believe the presumptive GOP nominee will be bad for the global deal climate, according to Intralinks, an M&A content collaboration company that said it collected results from 1,500 respondents. He's viewed less favorably for the deal climate than his chief Democratic rival, Hillary Clinton.

"People don't like uncertainty and change. There's a lot of rhetoric going around...it's just that uncertainty that's spooking deal makers outside the U.S.," Matt Porzio, vice president of M&A strategy at Intralinks, said in an interview. "It's been a good run and they want to see things stay as stable as they can be." Indeed, 2015 was a record-breaking year for deals, with the global total just topping $5 trillion, according to data services firm Dealogic. However, 2016 has been a different story, with volume sliding 19 percent from the year-ago total amid a tighter regulatory environment. Withdrawn deals in the U.S. have hit record levels, with $378.2 billion worth of mergers taken off the table, Dealogic reported, already a record as officials crack down on companies seeking to switch their domiciles to lower-tax countries, a practice known as inversions. Trump's unfavorables are lower among U.S. experts, with 46 percent believing he'll be negative for M&A, against 31 percent who view him as a positive and 23 percent seeing him as having no impact, according to Intralinks.