BERLIN : Volkswagen, Northvolt's top shareholder, has significantly written down its 21 per cent 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