Investopedia's Case Study: The Collapse of Lehman BrothersOn September 15, 2008, Lehman Brothers filed for bankruptcy. With $639 billion in assets and $619 billion in debt, Lehman's bankruptcy filing was the largest in history, as its assets far surpassed those of previous bankrupt giants such as WorldCom and Enron. Lehman was the fourth-largest U.S. investment bank at the time of its collapse, with 25,000 employees worldwide.