15. Berkshire Hathaway Warren Buffett's $50 billion portfolio earned $11 billion last year, up 29% from the previous year. In July 2006, the legendary investor announced plans to donate the bulk of his $40 billion fortune to the Bill & Melinda Gates Foundation. | Wal-Mart retakes the No. 1 slot on the Fortune 500 this year. See where America's largest corporations rank, and why. (more) See the 37 companies that made both the Fortune 1000 and Best Companies to Work For lists this year. (more) |