Every few years, a banker acting on his own begins to make trades not authorized by his firm. He risks his company's assets in the hopes of making a killing and probably a huge bonus. These traders usually end up losing large sums and being fired then investigated by the local financial regulators.

Earlier this week, a single trader pushed the price of crude from $71 to $73.50 in one hour. The higher price was the top amount paid for oil this year. In an exclusive report, the Financial Times writes that PVM Oil Associates, the world's largest over-the-counter oil brokerage, said on Thursday it had been the "victim of unauthorised trading."