Doug Parker (L), Chairman and CEO of US Airways, and Thomas Horton, Chairman, President and Chief Executive Officer of American Airlines, speak during a news conference to announce the merger of the two airlines in Dallas, Texas.  - 

Hostile takeovers, backroom deals and selling companies have long been a part of the finance world. But in the past few decades, M&As have grown into an enormous business. Deals between corporations can now shake entire industries. 

John Weir Close, author of A Giant Cow-tipping by Savages: The Boom, Bust, and Boom Culture of M&A, says the early days of M&As in the 1970s and 1980s were filled with gritty details of backroom drama and wild personalities.

"M&A are a much more sober business," Close says. "And the people doing it are much more sober now." 

Although the M&A industry is much tamer now, the relics of risk-taking still remain. "Early M&A spread almost an infection into modern Wall Street," Close says. "I think that the financial crisis is a direct descendent of the 1980s. There's a direct link between investment bankers urging clients to buy more and bid more, to investment bankers selling subprime mortgages, that brought us to where we are today."



Follow Kai Ryssdal at @kairyssdal