Lehman Brothers Inc. was an American global financial services firm founded in 1850. Before filing for bankruptcy in 2008, Lehman was the fourth-largest investment bank in the United States, with about 25,000 employees worldwide. It was doing business in investment banking, equity, fixed-income and derivatives sales and trading, research, investment management, private equity, and private banking. Lehman was operational for 158 years from its founding in 1850 until 2008.