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.

Volkswagen (OTCPK:VWAGY) has taken a major writedown of its 21% stake in the Swedish battery company, Northvolt, Reuters reported Monday, citing two sources. The writedowns at the German automobile giant were done throughout the current financial year,

Volkswagen bet big on European-made batteries a few years ago with two massive investments in Northvolt, the Swedish manufacturer. Now the automaker’s €1.4 billion stake is worth less than half that, according to Reuters. The write-downs occurred throughout the current fiscal year as the situation at Northvolt deteriorated.