5. Bruno Iksil (Loss: $3 billion)
Bruno Iksil was a trader for the JPMorgan Chase in the London office, who was nicknamed Voldemort for his influence on Wall Street and London Whale for his risky trading habits. Iksil was so bullish and powerful that some of his trades can move the index. He bet a large amount of money that some companies might default, potentially earning JPMorgan a few hundred million dollars in windfall. After a series of loss related to derivatives, in May 2012, he was removed from the company’s trading team.