The Oracle of Omaha has a golden goose in Goldman Sachs. Warren Buffett has bagged nearly $10 billion in interest, fees and dividends on the $5 billion lifeline he extended to the investment bank in 2008, during the darkest days of the financial crisis. Buffett's bonanza comes after Goldman got the green light from the Federal Reserve yesterday to buy back $5 billion of preferred shares. Goldman was among the banks that won government approval to return money to investors after undergoing a new round of "stress tests" to determine their financial stability. Within minutes of learning they had passed, 19 financial institutions that had been forced to cut shareholder payouts to conserve capital during the financial crisis, announced they would boost dividends. Redeeming Berkshire Hathaway's stake has been a priority for Goldman because of the fat 10 percent dividend that made Buffett nearly $500 million a year.