They take enforcement seriously at the Federal Bureau of Investigation. They get Gordon Gekko to warn off hedge fund managers from trading on inside information, and they tap the phones of suspects.
Compared with that, hedge fund managers in Mayfair and Geneva, where Philippe Jabre moved after being fined £750,000 for market abuse at the GLG hedge fund in 2006, have things easy. The small minority that breaks the rules has a much lower chance of either being caught or, when caught, jailed.
Legitimate banks choose financial centres according to national loyalty, tax and regulation but an insider trader will logically settle outside New York or Greenwich, Connecticut. Hedge funds are well versed in risk and reward, and the risks of illegality are now greater in the US than in Europe.