2013 is turning out to be a pretty good year for Warren Buffett. Year-to-date, the octogenarian billionaire has seen his firm, Berkshire Hathaway, rally more than 25.6 percent. That's almost double the returns that investors have gotten from the broad market over that same period.
And a lot of that upside in Berkshire's price has to do with Buffett's $85 billion stock portfolio.



