Sports car specialist Porsche has exercised an option to increase its shareholding in German volume car-maker Volkswagen to 30.9 per cent. The move comes after the European Court of Justice ruled to scrap a law preventing any one company from being able to wield more than a fifth of the voting rights on the VW Group's supervisory board. Porsche now owns almost a third of VW, and as a result, Porsche co-owner Ferdinand Piech, already chairman on the VW supervisory board, takes on a greater interest in the group. More importantly for Piech, between Porsche and 20.8 per cent shareholder the state of Lower Saxony, more than half of Volkswagen will remain in German hands.Already the largest individual shareholder in VW, increasing its stake beyond 30 per cent means that Porsche is required by German law to lodge a bid for the entire company; it should do so this week, but only as a token gesture. Over the weekend, Porsche advised that it would be offering to buy the remaining 69.1 per cent of the VW Group just over €100 per share; on Friday afternoon, they were valued at €117. That, financial experts say, is all the proof you need of that fact that Porsche isn't interested in taking over VW entirely.