The mighty Man Group has a small problem. Though the London-based giant manages close to $80 billion in alternative assets, it has had scant luck gaining much of a foothold in the U.S. The firm's specialty — structured products in guaranteed funds, which promise to preserve investor capital no matter what — makes up almost half of Man's business. But such offerings don't appeal much to U.S. institutional investors, most of which consider them high on fees and low on returns. Man has historically done little to alter that perception. In December 2007, however, the firm chose Uwe Eberle, 43, to replace the retiring John Kelly as CEO of New York–based Man Investments, USA, signaling a change of course. Eberle’s cheerful and adventurous nature — he took a year off in 1999 and traveled South America with only a backpack and some climbing gear — doesn’t disguise an assertive and...