In the 44 years Warren Buffett has been at the helm of Berkshire Hathaway (NYSE:BRK-A) (NYSE:BRK-B), he's remained remarkably consistent in several key areas, including a long-term focus, preference for top-notch management, staying in his circle of competence, humility, and a love for Cherry Coke.

Ironically, one of Buffett's greatest consistent traits is his willingness to change when he sees a better way of doing things.

At the Berkshire Hathaway annual meeting in Omaha, Motley Fool analyst Matt Koppenheffer and I spoke with Andy Kilpatrick about all things Buffett. In this video Kilpatrick, the author of Of Permanent Value: The Story of Warren Buffett, talks about two major changes he's seen in the Oracle of Omaha.

The first is a shift away from the Benjamin Graham method of buying good businesses at great prices, and toward paying fair prices for great businesses. The second is the preference to buy whole businesses instead of stocks.

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Rex Moore owns shares of Berkshire Hathaway. The Motley Fool recommends Berkshire Hathaway. The Motley Fool owns shares of Berkshire Hathaway. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.