Citi (C) Taps Goldman's (GS) Mann to Lead Credit-Index Trading GroupStreetInsider.com (subscription)Citigroup (NYSE: C) is said to have hired Goldman Sachs' (NYSE: GS) John "Jay" Mann to head index trading within credit markets unit. He will report to Citi's head of global trading Brian Archer, sources told Bloomberg . Mann was said to have been [...]