Corporate deal-making reached a fever pitch in 2015, with new data revealing merger and acquisition activity totaled $4.5 trillion this year, breaking an all-time annual record. According to Thomson Reuters Deals Intelligence, that's a 42% increase over the prior year. 

"It's  the most prolific year that we've ever seen since we began tracking M&A in 1980," said Matthew Toole, Director of Deals Intelligence.

The activity was driven by mega-deals priced at $5 billion and above. There was record M&A activity in five sectors: health care, consumer products, retail, technology and industrials. Additionally, for the first time ever, there were three consecutive trillion-dollar-plus quarters in 2015, thanks to large deals such asPfizer(PFE) - Get Report and Allergan's(AGN) - Get Report $191.5-billion merger and Anheuser-Busch InBev's(BUD) - Get Reportplanned $120.8 billion merger withSABMiller (SBMRY) .

"Companies are looking for revenue growth, they're also looking to streamline and get rid of businesses that are non-core," explained Toole. "And as companies consolidate at the top, it filters down to other companies looking to see what do we need to do to compete in this landscape."

Toole said it's hard to say that the M&A cycle is peaking. "There's no real indicator that this will end. There's still cheap financing, there's still lots of cash on the books," he said. "2016 looks to be more of the same as we enter the new year." 

Toole said that while valuations are higher than they've been compared to previous years, some argue that because there is so much strategic M&A going on right now, the valuations are justified.

The M&A boom has been good for bankers, and Toole said that merger fees are up 5% and are at an eight-year high. 

"Goldman Sachs(GS) - Get Report , Morgan Stanley(MS) - Get Report , JPMorgan(JPM) - Get Report -- are all seeing trillion dollars in advisory credit in our overall league tables," said  Toole, who added that some boutique firms have also benefited. He pointed to Zaoui, Qatalyst, and Tudor Pickering as among those smaller investment banks that have seen strong business in the current environment.