BERLIN (Reuters) -Top Volkswagen shareholder Porsche SE expects to write down 7 billion to 20 billion euros ($20.98 billion) on its investment, it said on Friday, in the latest sign of how VW's cost crisis has shaken investor faith in the carmaker.

It also expects an impairment on its investment in luxury carmaker Porsche AG, majority-owned by Volkswagen, of up to 2 billion euros, based on analyst expectations for the two companies.

Volkswagen AG, which is in the midst of tense negotiations with unions over cost cuts at its German operations, was unable to complete its financial planning for the year, forcing Porsche SE to rely on analysts' expectations for its forecasts.

The investment vehicle, jointly owned by the Porsche and Piech families, said it now expects its group result after tax in 2024 to be "significantly negative", withdrawing its forecast of 2.4 billion to 4.4 billion euros.

However, it still expects to distribute a dividend for the financial year, it said.

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