Warren Buffett, chairman and CEO of Berkshire Hathaway, sings with University of Nebraska cheerleaders prior to the annual shareholders meeting in Omaha, Neb., Saturday, May 5, 2012. Berkshire Hathaway is holding it's annual shareholders meeting this weekend. (AP Photo/Dave Weaver)

Photo by: Dave Weaver

Warren Buffett, chairman and CEO of Berkshire Hathaway, sings with University of Nebraska cheerleaders prior to the annual shareholders meeting in Omaha, Neb., Saturday, May 5, 2012. Berkshire Hathaway is holding it's annual shareholders meeting this weekend. (AP Photo/Dave Weaver)