Ken Griffin, Illinois
Griffin's net worth of $11.7 billion comes from the hedge fund industry. He started trading in his Harvard dorm room in 1987 and now is the founder and CEO of Citadel, a hedgef fund that manages $32 billion in assets. He also owns Citadel Securites, one of Wall Street's most successful makers.
Carl Cook, Indiana
Cook can thank the medical device industry for his $9.5 billion net worth. He is the CEO of Cook Group, a $2.4 billion revenue manufacturer. His parents started the business in their Bloomington apartment in 1963, and Cook took over after his father's death in 2011.