Year-to-year variances, however, cannot consistently be in our favor. Even if our partially-owned businesses continue to perform well in an economic … - Warren Buffett

The strategy we've adopted precludes our following standard diversification dogma. Many pundits would therefore say the strategy must be riskier than that employed by more conventional investors. We disagree. 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."

Derivatives are like sex. It's not who we're sleeping with, it's who they're sleeping with that's the problem.

Just because Charlie and I can clearly see dramatic growth ahead for an industry does not mean we can judge what its profit margins and returns on capital will be as a host of competitors battle for supremacy. At Berkshire we will stick with businesses whose profit picture for decades to come seems reasonably predictable. Even then, we will make plenty of mistakes.