Greenlight Capital is a hedge fund which was founded by David Einhorn. Einhorn's commentary on the financial position of Lehman Brothers in early 2008, and Greenlight's short selling of Lehman stock, foreshadowed Lehmans' collapse.

Greenlight invests primarily in publicly traded North American corporate debt offerings and equities. It also manages a fund of funds and a private equity fund through its affiliates, Greenlight Masters and Greenlight Private Equity Partners. It also operates Greenlight Capital Re, a property/casualty reinsurer.

Unlike other funds, Greenlight does not use borrowed money, or leverage. The firm does not generate large trading volumes.

Founded in 1996 with $900,000 of capital (half borrowed from Einhorn's parents), Greenlight has generated greater than a twenty-five percent annualized net return for its partners and investors over its life.