As the founder and CEO of Citadel Investment Group, Ken Griffin has turned $1 million in seed money into the Goldman Sachs of the hedge fund industry. One of the most powerful and wealthiest investors on Wall Street, Griffin started Citadel in his early 20s. Known for its astonishing technological capabilities, Citadel’s use of computer models, mathematics, and historical data has turned the company into a $22 billion hedge fund with returns averaging more than 20%. The company has also benefited from Griffin’s excellent instinct; his esoteric investments and unconventional bids have made him one of the most watched figures in the industry. Griffin is now turning Citadel—which accounts for 7% of stock trading volume in the United States each day—into more than one of the world’s most dominant hedge funds.