The mega-merger is back.
For the corporate takeover business, the last half-decade was a fallow period. Wall Street deal makers and chief executives, brought low by the global financial crisis, lacked the confidence to strike the audacious multibillion-dollar acquisitions that had defined previous market booms.
Cycles, however, turn, and in the opening weeks of 2013, merger activity has suddenly roared back to life. On Thursday, Berkshire Hathaway, the conglomerate run by Warren E. Buffett, said it had teamed up with Brazilian investors to buy the ketchup maker H. J. Heinz for about $23 billion. And American Airlines and US Airways agreed to merge in a deal valued at $11 billion.
Those transactions come a week after a planned $24 billion buyout of the computer company Dell by its founder, Michael S. Dell, and private equity backers. And Liberty Global, the company controlled by the billionaire media magnate John C. Malone, struck a $16 billion deal to buy the British cable business Virgin Media.