Which US investment bank's September 2008 bankruptcy became the largest in American history?

Lehman Brothers filed for bankruptcy on 15 September 2008, becoming the largest bankruptcy in American history at that time.

The investment bank had built a major business in mortgage-related securities and real estate finance. As US house prices fell and subprime mortgage losses spread, confidence in Lehman's balance sheet deteriorated. The firm could not secure a buyer or sufficient government-backed rescue and sought Chapter 11 protection.

Lehman's failure intensified the global financial crisis. Money-market funds, banks, insurers, and investors became more cautious about lending to one another. The bankruptcy was followed by emergency interventions, including the rescue of AIG, the sale of Merrill Lynch to Bank of America, and large government support programs.

Lehman is often described as the moment the 2008 crisis became dramatically worse, although the crisis had been developing for years. Bear Stearns had already failed in March 2008, but Lehman's bankruptcy was much larger and had wider immediate repercussions.