Lehman Brothers' decision to build an energy trading business did not come as a great surprise. My reaction was to ask why they didn't do it sooner instead of allowing Goldman Sachs and Morgan Stanley to have the field almost to themselves.

We know that commodities traders are among the highest paid people on Wall Street, which confirms that profit margins are sky-high. We know Goldman and Morgan Stanley use every incentive to ring-fence their best people from being recruited by other banks.