Earlier this year, it emerged that the London Metals Exchange had been holding a bunch of bags filled with stones instead of the nickel needed to back trades for major commodities players, including Trafigura. Before that, commodities trader Mercuria was given painted rocks instead of the copper it expected.
In short, the commodities world is no stranger to fraud. But what is it about the business of trading, moving and storing commodities that makes it so susceptible to scandal?