A former Citigroup Inc. trader accused of rigging the foreign-exchange markets was a "golden boy" in demand at the bank for his knowledge of markets and ability to communicate with others, a former colleague said in his defense.
The ex-trader, Rohan Ramchandani, is on trial in federal court in New York, charged with conspiring with two other former traders, Richard Usher of JPMorgan Chase & Co. and Christopher Ashton of Barclays Plc, to coordinate trades and fix currency prices in the $5.1 trillion-a-day foreign-exchange market in a group known as "The Cartel."
On Tuesday, Carly Hosler, a former Citigroup trader who worked