A former Deutsche Bank trader convicted of wire fraud in the U.S. is suing the bank for £12 million ($16.2 million) for training him to break the rules. James Vorley, who worked in DB’s London office, claims senior managers at the bank instructed him to use a trading strategy that resulted in his prosecution.

Ruth Prickett graduated from Cambridge University with a BA hons in History and has specialized in business and finance journalism for the past 20 years. She was editor of Financial Management, the magazine...