In uptown New York City, Citadel hedge fund manager Kenneth Griffin closed on a new 24,000-square-foot penthouse with a view across Central Park. Griffin’s purchase complements his other recent house buys in Chicago ($58 million), Miami Beach ($60 million) and a $122 million house in central London. The U.S. tax code allows hedge fund investors like Griffin to pay only 23.8 percent tax on their gains thanks to the “carried interest” provision. By comparison, middle-class workers pay a tax rate of 22 percent on income from $38,701 to $82,500.