BERLIN (Reuters) - Volkswagen, Northvolt's top shareholder, has significantly written down its 21% stake in the Swedish battery cells maker that filed for bankruptcy protection in the United States last week, two people familiar with the matter said.

Several of Northvolt's top shareholders have been cutting or reviewing the value of their holdings in the firm, which has kept missing production targets as an expected boom in electric vehicle demand has failed to materialise in Europe.

The writedowns at Volkswagen were done throughout the current financial year, the people said, without giving the stake's current value.

At the end of 2023, Volkswagen reported the book value of its shareholding in the Swedish firm at 693 million euros ($726 million), down nearly a quarter from a year earlier.

That value dropped dramatically over the course of 2024, the people said. They declined to be identified because the information is confidential.

Volkswagen expects an operating profit margin of 5.6% and net cash flow in the automobile division of 2 billion euros in 2024.

Volkswagen declined to comment on the writedowns, reiterating that it would not make any statements on the impact Northvolt's filing will have on the company.

The Financial Times on Saturday reported that funds managed by Goldman Sachs ( GS ), Northvolt's second-largest shareholder with a 19.2% stake, would write off their $900 million stake in Northvolt to zero by year-end, citing letters to investors.

Swedish pension fund AMF, also among Northvolt's top 10 shareholders, said it was regularly reviewing and adjusting the values of its unlisted holdings, but offered no details when asked about its Northvolt stake.

"As is obvious to everyone, the value of Northvolt is considerably lower than it was compared to a year ago," an AMF spokesman said, adding the pension fund had invested the equivalent of 1.95 billion Swedish crowns ($178 million) through the years.

($1 = 0.9550 euros)

($1 = 10.9793 Swedish crowns)