Citibank has a big problem: It mistakenly wired roughly $175 million to Brigade Capital Management, and the hedge fund hasn't returned the money. The US banking giant filed a lawsuit Monday in the Southern District of New York, seeking the return of funds that it said were transferred in an "operational mistake." Citibank said in court documents that it meant to send Brigade Capital around $1.5 million in interest payments on a loan the hedge fund made to troubled cosmetics company Revlon. Instead, it wired roughly 100 times that amount of its own funds to the hedge fund. Other Revlon...