If you think you ever had a bad day at work, be thankful you are not Jérôme Kerviel, the French financial trader who lost €4.9 billion for his bank. In American dollars that’s 7.2 billion. It was all lost, essentially, in a single day. Kerviel was making bets that European stocks would continue to go up, and thought he found the perfect system for making winning trades. Indeed, his early trades did net money, and he began wagering ever-larger amounts even as the markets turned against him.

On this day, January 24th, in 2008, Kerviel was finally detected and stopped. A quick investigation uncovered something around €1 billion in unauthorized positions, and the bank began to reverse them just as fast as they could.

They could not have picked a worst time to do it, however. Events in the U.S. and elsewhere in the world brought the markets down. Selling into a down market is bad under ordinary circumstances, but unwinding Kerviel’s trades made it much worse – nearly five times worse. Kerviel meanwhile was sentenced to five years in jail and barred from trading ever again. He was not ordered to repay the bank for losses – at his salary, that would have taken 170,000 years.