Lehman Brothers became the defining institutional symbol of the 2008 global financial crisis when it filed for bankruptcy on 15 September 2008.
At the time, Lehman was the fourth-largest investment bank in the United States. Its failure followed heavy exposure to mortgage-related assets and a collapse in confidence after years of rapidly expanding housing and credit markets.
The bankruptcy was the largest in U.S. history by assets at the time, with about $639 billion in assets listed in the filing. Its sudden failure shocked banks and investors because it demonstrated that a major financial institution could be allowed to disappear.
The consequences spread through global credit markets. Governments and central banks introduced emergency measures, while stock markets fell sharply. The crisis also led to major regulatory changes, including the 2010 Dodd–Frank Act in the United States.