It's not just a coincidence that Wall Street is full of men and women from France. French education puts a strong emphasis on pure mathematics and some French universities have developed programs specializing in the complex modeling of derivatives. Derivatives are a financial instrument based on math that is nearly impossible to understand. The mathematical wizardry works like this: quantitative analysts build models for, say, a financial product that will protect investors against various shifts in the market. A second group puts together financial products based on the models. Traders buy and sell various elements in a package based on the models and structures they have to work with. Given the amount of people and work involved, it's improbable a rogue trader can make billion-dollar bets on his own. However, the outside world hears only about the derivatives that go wrong.