Having more than 75 percent would allow it to seal a so-called domination contract giving it full financial control.

In Germany, a minority investor that owns 25 percent of a company's shares can block strategic decisions, but in the case of VW that level is currently set by law at 20 percent, the amount owned by the state of Lower Saxony, where VW is based.

Porsche built up its stake in the much bigger VW through the use of stock options that allowed it to catch markets by surprise last year with the size of its holding. VW's works committee is wary of the takeover however and of Porsche boss Wendelin Wiedeking, who has crossed swords with trade unions, which are extremely powerful at VW.

VW posted sales of 109 billion euros in 2007, while Porsche, which employs 11,600 workers, reported sales of seven billion euros in its 2006-2007 fiscal year.