5. Greg Jensen
40u40 main greg jensen
Age: 38

CEO, Bridgewater Associates

Jensen has come a long way at Bridgewater, the world's largest hedge fund. In August the former intern became chief executive of the $130 billion, 1,200-person hedge fund firm. He remains co-chief investment officer with founder Ray Dalio, and together the team recently won the coveted Hedge Fund Firm of the Year from Institutional Investor. Jensen and his fellow execs constantly fine-tune the firm's investing bible -- the legendary set of rules that guide the firm's every investment move -- reflecting their belief that the world is now driven by policy, not markets.

Om: Jensen started meditating last year, finally giving into Dalio's recommendation that he try it. The result? He's a convert. He says he has greater clarity and focus. --Katie Benner

  @FortuneMagazine - Last updated October 17 2012 05:11 PM ET
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