Lehman Brothers filed for bankruptcy in September 2008, intensifying the global financial crisis.
The investment bank submitted its Chapter 11 petition on September 15, 2008, after losses tied especially to mortgage-related securities and real-estate lending. With more than $600 billion in assets, it became the largest bankruptcy filing in U.S. history at that time.
Lehman's collapse shocked financial markets because the firm was deeply connected to banks, funds, and other institutions worldwide. Uncertainty about which institutions were exposed to Lehman's obligations contributed to a severe credit freeze. Equity markets then fell sharply, and governments launched emergency measures to stabilize the financial system.
Lehman was not the first major financial firm to fail in the crisis. Bear Stearns had been rescued in March 2008, while the U.S. government later supported institutions including AIG. The bankruptcy is often treated as a pivotal event, not the sole origin, of the 2008 crash.