Which American billionaire is the founder of the hedge fund Citadel?

Ken Griffin is the American billionaire who founded the hedge fund Citadel. He established Citadel in Chicago in 1990 after developing an early trading operation while studying at Harvard.

Griffin began trading from his Harvard dormitory, using a satellite dish to obtain stock-market data and raising money from family members and other backers. His first fund benefited from positions taken around the 1987 market crash. After graduating, he worked with investor Frank Meyer before launching Citadel with about $4.6 million in assets.

Citadel grew from a hedge fund into a major global investment firm managing money across strategies including equities, fixed income, commodities and quantitative trading. Griffin later founded Citadel Securities, a separate market-making business that became one of the largest providers of liquidity in U.S. markets.

A common mix-up is confusing Citadel with Citadel Securities: Griffin founded both, but Citadel is the hedge fund and Citadel Securities is the market maker. David Tepper, Bill Ackman and John Paulson are also prominent investors, but none founded Citadel.