Buffett on Diversification, Risk, and Focus

Diversification is a protection against ignorance. It makes very little sense for those who know what they’re doing. I can’t be involved in 50 or 75 things. That’s a Noah’s Ark way of investing – you end up with a zoo that way. I like to put meaningful amounts of money in a few things.
We believe that a policy of portfolio concentration may well decrease risk if it raises, as it should, both the intensity with which an investor thinks about a business and the comfort-level he must feel with its economic characteristics before buying into it. In stating this opinion, we define risk, using dictionary terms, as ‘the possibility of loss or injury.’
~Warren Buffett

Every professional wrestles with focus. You’re smart enough to do many things. But to achieve, to really achieve, you need to focus on a few key priorities.

Yeah, I need constant reminding here.