“One of the inane things [that gets] taught in modern university education is that a vast diversification is absolutely mandatory in investing in common stocks. That is an insane idea. It's not that easy to have a vast plethora of good opportunities that are easily identified. And if you've only got three, I'd rather it be my best ideas instead of my worst.”

“You don't need all this damn diversification. You're lucky if you've got four good assets. … If you're trying to do better than average, you're lucky if you have four things to buy. And to ask for 20 is really asking for egg in your beer.”

Condensed from a longer answer (the ellipsis marks an omitted jab at finance professors); 'egg in your beer' is an old idiom for wanting more than you deserve.

“In the United States, a person or institution with almost all wealth invested, long term, in just three fine domestic corporations is securely rich.”

“But when you know you have an edge, you should bet heavily. When you know you're right. Most people don't teach that in business school. It's insane. Of course you got to bet heavily on your best bets.”

“How many of you have 56 brilliant ideas in which you have equal confidence? Raise your hands, please. How many of you have two or three insights that you have some confidence in? I rest my case.”