The company said it made 6.83 billion euros ($8.7 billion) from trading in VW options, plus another 1 billion euros from the rising value of its Volkswagen stake, in the fiscal year that ended in July.

This helped Porsche to increase its pre-tax profit by 46 per cent to 8.57 billion euros, even exceeding the company's revenues.

Analysts dubbed Porsche a "hedge fund", and even one of the most successful ones in the world, at a time when other carmakers are struggling with a sharp downturn.

"If they now increase their stake [in VW] to more than 50 per cent and cash in the remaining 25 per cent of the options, they would make hedge funds and banks pay for the whole takeover," said Arndt Ellinghorst, analyst at Credit Suisse.

Klaus Kaldemorgen, head of DWS, one of Germany's largest institutional investors, alleged that Porsche had used massive information asymmetries at the expense of other investors.

"We vehemently reject the accusation of share price manipulation," Porsche said in a statement last week.