Kenneth Griffin is an American hedge fund manager and billionaire founder of Citadel LLC. He started Citadel in 1990 with $8 million and has built it into one of the largest hedge funds in the world managing over $39 billion in assets. Griffin has a net worth estimated between $16-22 billion, making him the 2nd richest person in Illinois. He oversees Citadel's asset management, market making, and technology businesses from the firm's headquarters in Chicago.