Lehman Brothers Holdings Inc. ( ) (pronounced IPAEng: ˈliːmən) was a global financial-services firm active prior to its bankruptcy and sale in 2008. The firm did business in investment banking, equity and fixed-income sales, research and trading, investment management, private equity, and private banking. It was a primary dealer in the U.S. Treasury securities market. Its primary subsidiaries included Lehman Brothers Inc., Neuberger Berman Inc., Aurora Loan Services, Inc., SIB Mortgage Corporation, Lehman Brothers Bank, FSB, Eagle Energy Partners, and the Crossroads Group. The firm's worldwide headquarters were in New York City, with regional headquarters in London and Tokyo, as well as offices located throughout the world.

On September 15, 2008, the firm filed for Chapter 11 bankruptcy protection; the filing marks the largest bankruptcy in U.S. history. The following day, Barclays PLC announced its agreement to purchase, subject to regulatory approval, Lehman's North American investment-banking and trading divisions along with its New York headquarters building. On September 20, 2008, a revised version of that agreement was approved by Judge James Peck.

On September 22, 2008, Nomura Holdings, Inc. announced it agreed to acquire Lehman Brothers' franchise in the Asia Pacific region including Japan and Australia. The following day, Nomura announced its intentions to acquire Lehman Brothers' investment banking and equities businesses in Europe and the Middle East. A few weeks later it was announced that conditions to the deal had been met, and the deal became legally effective on Monday, 13 October. In 2007, non-US subsidiaries of Lehman Brothers were responsible for over 50% of global revenue produced.

Under the Lehman family (1850–1969)

In the 1850s Southern United States, cotton was one of the most important crops. Capitalizing on cotton's high market value, the three brothers began to routinely accept raw cotton from customers as payment for merchandise, eventually beginning a second business trading in cotton. Within a few years this business grew to become the most significant part of their operation. Following Henry's death from yellow fever in 1855, Geisst, Charles R. The Last Partnerships. McGraw-Hill, 1997, page 50 the remaining brothers continued to focus on their commodities-trading/brokerage operations.

By 1858, the center of cotton trading had shifted from the South to New York City, where factors and commission houses were based. Lehman opened its first branch office in New York City's Manhattan borough at 119 Liberty Street, and 32-year-old Emanuel relocated there to run the office. In 1862, facing difficulties as a result of the Civil War, the firm teamed up with a cotton merchant named John Durr to form Lehman, Durr & Co. Birmingham, Stephen. Our Crowd- The Great Jewish Family's of New York. Harper and Row, 1967, page 77 Bernhard, William, L., Birge, June Rossbach Bingham, Loeb, John L., Jr.. Lots of Lehmans - The Family of Mayer Lehman of Lehman Brothers, Remembered by His Descendants. Center For Jewish History, 2007, page 8 Following the war the company helped finance Alabama's reconstruction. The firm's headquarters were eventually moved to New York City, where it helped found the New York Cotton Exchange in 1870; Wechsberg, Joseph. The Merchant Bankers. Pocket Books, 1966, page 235 Emanuel sat on the Board of Governors until 1884. The firm also dealt in the emerging market for railroad bonds and entered the financial-advisory business.