Former derivatives broker, Nicholas "Nick" Leeson, has an estimated net worth of $9 million. He is best known for being the captain behind the fraudulent, unauthorized speculative trading that caused the collapse of Barings Bank, the United Kingdom's oldest investment bank, for which he was sent to prison. In the early 1990s, Leeson, a trader who worked for the British investment bank Barings, made numerous risky moves on the Singapore International Money Exchange (SIMEX), hiding his losses from the firm in a secret account. By the time Barings discovered the ruse, it was too late: The bank was $1.3 billion in debt and had to shut its doors. Leeson, who served more than six years in prison, publicly owned up to his wrongdoing in two books about the scandal and its fallout.