The first and third richest people in the world, Gates and Buffett have a net worth of $79.2 billion and $72.7 billion, respectively. The former has built his fortune through Microsoft (MSFT) and the latter with Berkshire Hathaway (BRK.A) (BRK.B) .
The billionaires have joined forces on a number of occasions, from pledging their fortunes to charity to lobbying Congress on immigration. At the 2015 Berkshire Hathaway Annual Shareholders Meeting in Omaha, they competed in a newspaper toss and played some ping pong.
In 2013, Gates called his dialogue with Buffett "invaluable" in an essay penned in the Oracle of Omaha's honor. He also discussed Warren Buffett's methods of investing. "He talks about looking for a company's moat -- its competitive advantage -- and whether the moat is shrinking or growing," he wrote. "He says a shareholder has to act as if he owns the entire business, looking at the future profit stream and deciding what it's worth. And you have to be willing to ignore the market rather than follow it, because you want to take advantage of the market's mistakes -- the companies that have been underpriced."