MF Global used to be known as Man Financial, and it had a reasonably good reputation. It did a humdrum business placing commodities trades for fund managers as well as farmers, grain dealers and others whose livelihoods depend on the vagaries of commodity prices.

Some hedge fund managers have made big bucks trading oil futures - George Soros is one.

The recommendation is to go for commodities such as soy and cotton, which you can benchmark against global prices.

The problem with the focus on speculators, as was demonstrated during the financial crisis, is that it tends to divert attention from the real villains. During the financial crisis, the villains were the actions of the banks, not the speculators betting on bank share prices.

With such enormous bucks devoted to trading in oil and other commodities, the distortions that they cause have been exacerbated.

One guy, his whole livelihood is rolling back odometers for dealers. He's figured out how to do it. It just takes longer.