A wheat trader at MF Global, one of the world’s biggest commodities brokerages, lost $141.5m by making “unauthorised” trades, the company reported on Thursday, in the latest trading controversy to hit global markets.

“This is embarrassing for us and it’s upsetting,” said Kevin Davis, chief executive of MF Global, which said it had “terminated” the employee, who it identified as Evan Dooley, 40, from the group’s Memphis office.