...when I start reading about Andrew Hall, the Citigroup energy trader fighting for his $100m bonus, there is always a vague, unanswered question floating around at the back of my mind: what does this person actually do to earn so much?..

...These simple wagers are what netted the senior trader approximately $23,000 per hour, $274,000 per day, or $100m per year.

...Now here comes the most interesting bit: Mr Hall appears not just to have been shuffling abstract pieces of paper or playing with numbers on a computer screen. Phibro, now a division of Citigroup, was buying up oil and stockpiling it on floating depots. This was worth the investment if the price of oil rose more than the cost of storage. In fact, many investment banks, from Morgan Stanley to Goldmans, have in recent months been removing supply in a similar way to OPEC, the cartel of oil producing countries that tries to support prices by cutting production.

Most experts think the volatility of the oil price has nothing to do with speculators pushing up prices by hoarding. Traders heap scorn on the US government’s Commodity Futures Trading Commission for scrutinising the role of those who buy up oil as an investment and do not need to use the commodity in their line of business. But CFTC officials are currently conducting hearings with industry players, and in the UK, the Financial Services Authority is taking a close look at the oil market.

The experts and analysts are most probably right. Plenty of things affect the oil price, not least supply and demand. Speculation is likely to cause only small swings in the market, most studies conclude.