On which date did Lehman Brothers file for bankruptcy, a defining shock of the 2008 stock-market crash?

Lehman Brothers filed for bankruptcy on September 15, 2008, becoming a defining shock of the global financial crisis.

The filing was the largest bankruptcy in U.S. history at the time. Lehman had accumulated substantial exposure to mortgage-related securities and had relied heavily on borrowed money. As the U.S. housing market deteriorated and mortgage losses spread, investors increasingly doubted the firm’s ability to survive.

The bankruptcy intensified fear throughout financial markets. Credit became harder to obtain, financial shares fell sharply, and investors rushed toward safer assets. The failure followed the government-supported rescue of Bear Stearns earlier in 2008 and preceded the emergency rescue of insurer American International Group. These events helped turn a housing and banking crisis into a worldwide financial crisis.

Lehman’s failure is sometimes described as the single cause of the 2008 crash, but the downturn had deeper origins. Excessive leverage, weak mortgage lending, complex securities, and fragile financial institutions had already created serious vulnerabilities before the filing.