Warren Buffet's holding company, Berkshire Hathaway, is investing $5 billion in Goldman Sachs, in a strong sign of confidence that the U.S. financial system has hit rock bottom and has nowhere to go but up. Buffet has become one of the world's wealthiest men by investing in companies that he believes are undervalued by the market. By investing in Goldman Sachs, Buffet is signaling that he believes the investment bank has hit its lowest point, a sign that perhaps the U.S. financial system is stronger at its core than many believe. On Tuesday, Goldman Sachs CEO Lloyd Blankfein said, “We are pleased that given our longstanding relationship, Warren Buffett, arguably the world's most admired and successful investor, has decided to make such a significant investment in Goldman Sachs. We view it as a strong validation of our client franchise and future prospects.”