Justin Fox is an American financial journalist, commentator, and writer. He is a Bloomberg Opinion columnist, writing about business and economics. Formerly, he was editorial director of the Harvard Business Review Group for five years, and business and economics columnist for Time magazine. Fox's book, The Myth of the Rational Market (2009), traces the rise of the efficient-market hypothesis, and was a New York Times Notable Book of 2009, and was named the best business book of the year by Amazon.com.