Magnus Peterson, the head of the collapsed hedge fund business Weavering, has been found in the High Court to have defrauded investors and ordered to pay hundreds of millions of dollars in damages.
Mrs Justice Proudman ruled that Peterson, manager of the Weavering Macro Fixed Income fund, deceived clients and breached his duty of care to investors with a strategy that could not cope with the vagaries of markets at the height of the global credit crisis.
Damages of $450m (£289m) were awarded against him and against three other directors who were found liable for negligence, including his wife, Amanda.
The judge said Peterson, who has represented himself throughout the case, may have committed the fraud "out of a sense of invincibility, self-belief, and a gambler's mentality".
Liquidators of Weavering, which inflicted $350m losses on investors, launched a civil case against Peterson and other Weavering staff last year after the Serious Fraud Office dropped its investigation into the collapse, saying there was not a reasonable prospect of conviction.