Lehman Brothers was the investment bank whose bankruptcy on September 15, 2008, became a major turning point in the global financial crisis.
Lehman filed for Chapter 11 protection after suffering enormous losses tied to the US housing market and mortgage-related securities. With assets of about $639 billion, it was the largest bankruptcy filing in US history at the time. The failure intensified fear about the stability of banks and counterparties worldwide.
The crisis had already begun before Lehman's collapse. The failure of mortgage lenders, the rescue of Bear Stearns, and turmoil in credit markets were earlier warning signs. After Lehman, governments and central banks took extraordinary measures, including bank rescues, emergency lending, and large-scale monetary easing.
Lehman's bankruptcy is often treated as the start of the crisis, but that is an oversimplification. It was a dramatic accelerant in a crisis rooted in housing finance, leverage, securitization, and weak risk management.