Buffett Foundation and NoVo Foundation. WARREN BUFFETT'S ANNUAL LETTERS Shares of Berkshire Hathaway B-Class stock have gained over 30% this year, outpacing the S&P 500's 27% through Wednesday.

Billionaire Warren Buffett is viewed as one of the world's greatest investors, so his annual letters to Berkshire Hathaway shareholders are always read closely for lessons.