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A rogue employee at a unit of Mitsubishi Corporation used unauthorized trades to bet on oil markets.

Petro-Diamond Singapore, a Mitsubishi Corporation unit, "expects to book a loss of approximately $320 million from its trade of crude oil derivatives," Mitsubishi said.

The company discovered the trades in August and this week fired the employee and alerted the police in a complaint.

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A rogue employee at a unit of Mitsubishi Corporation used unauthorized trades to bet on oil markets, disguised them to look like "hedge transactions" with customers, and then lost millions when the market went south, the company says.

The employee, at Petro-Diamond Singapore, a Mitsubishi Corporation unit, had been building the positions since January, Mitsubishi said on Friday, confirming "that it expects to book a loss of approximately $320 million from its trade of crude oil derivatives."

The falling crude-oil price since July translated into "large losses," it said. The company discovered the trades in August and fired the employee and filed a police complaint this week.

Read more: Oil spiked a record 20% on the sudden attack to Saudi oil supplies

Oil has been in the headlines lately — a shock record 20% surge in oil prices on Monday was triggered by supply fears after an attack on Saudi oil fields last weekend.

The sudden move in Brent crude caught traders by surprise. The price of Brent crude has settled since Saudi officials sought to ease supply concerns, and Brent is now hovering at about 7% higher for the week.

Markets Insider

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