Porsche has been hit hard by the global recession
Porsche has seen its nine-month unit sales slump by more than a quarter after demand for its cars was hit by the worldwide recession.
Global sales at the German carmaker declined 28% to 53,635 vehicles between August 2008 and the end of April, compared with a year earlier.
On a financial basis, its sales fell 15% to 4.6bn euros ($6.4bn; £3.9bn).
The figures do not include those of Volkswagen (VW), in which Porsche increased its stake to 51% in January.
Porsche had planned to further increase its stake in VW to 75%, to gain a controlling interest, but talks with VW broke down in May amid reports Porsche could not raise the required funds.
Porsche will have to decide later whether it meets a Friday deadline that gives it the option to buy a further 20% of VW shares.
While most analysts expect Porsche will make a payment to extend the option period, there has been some speculation in the markets as to whether it can afford to do so.
If it doesn't extend its option, the banks who own these shares could sell them on the stock market.
Shares in VW ended down 3% on Friday, while Porsche lost 1.4%.
Separately, Porsche is also continuing talks with the Gulf state of Qatar over a possible investment by the Qatar Investment Authority, the country's state run sovereign wealth fund, in the firm.
Reports have suggested that the Qatar government wishes to buy a 25% stake in Porsche.
On a model-by-model basis, Porsche's nine-month decline in sales was most pronounced for its Boxster and Cayman models, which fell a combined 47%.
Sales of its core 911 model shed 18%, while those of its Cayenne four-wheel drive vehicle were down 25%.
Porsche said it had experienced falling demand across the world, but that the decline was most extensive in the US and Canada.
"In the first nine months of the ongoing fiscal year, the Porsche subgroup could not avoid the downward trend that has overtaken the worldwide automobile industry," said Porsche.