Societe Generale Rogue Trader

Jerome Kerviel, the Societe Generale trader whose unauthorized bets led to the biggest trading loss in history, told the bank cast had a ``complacent look'' on his practices. ``As long as we were winning and it wasn't too visible, things worked out, no one said anything,'' Kerviel said.

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Kerviel amassed 50 billion euros ($74 billion) in positions.
His job was to arbitrage small price differences between contracts, not to take bets on market directions.

Difficult to know exactly how things went, but there must be more to know on this story which is simply unbelievable.