Things have not been great lately for Warren Buffett and Berkshire Hathaway (BRKA) shareholders. BRK stock has dropped more than 20% since December and large Buffett holdings in the financial services area such as American Express, Wells Fargo, Moody's, and U.S. Bancorp are hurting his equity portfolio. Buffett has also taken some heat for publicly bashing the use of derivatives, but privately writing billions in credit default swaps.