Buffett decides a business is worth investing in because it will last. He purchased See's Candies with longtime business partner Charlie Munger in 1972 and spent more than $1 billion on Coca-Cola stock in 1988 — both of which turned out to be good bets and which he still owns today.
"We sort of know it when we see it," Buffett said during the the Berkshire Hathaway 2017 Annual Shareholders Meeting. "It would tend to be a business that for one reason or another we can look out five or 10 or 20 years, and decide that the competitive advantage that it had at the present would last over that period."
Once Buffett makes a purchase, he tends to hold on to it. "His approach is to be really sure of something before he buys it, and one of the ways he exercises that discipline is to sort of almost never sell. Not never sell, because he does sell stocks, but he sort of says to himself, 'I know I'm almost never going to sell it, I've really got to like it before I get into it,'" Buffett's biographer Roger Lowenstein, author of "Buffett: The Making of an American Capitalist," explained to Yahoo's Alexis Christoforous.