Investing icon Warren Buffett took his own advice Tuesday – getting “greedy when others are fearful” – when he ignored the banking-sector bonfire and slapped down a cool $5 billion for a stake in Goldman Sachs Group Inc. (GS). By literally putting his money where his mouth is, Buffett’s actions – and reputation as a shrewd bargain hunter – restored some of Goldman’s luster and helped bolster investor confidence in the U.S. banking system.