Power struggle at Volkswagen dents shares

• Volkswagen (VLKAY) Chairman Ferdinance Piech is facing criticism from within the company for a verbal attack on CEO Martin Winterkorn.
• Piech told Der Spiegel he has "distanced" himself from Winterkorn.
• Analysts think the power struggle at the top of the automaker is one of the biggest challenges it has faced over the last 20 to 30 years.
• A Volkswagen supervisory board meets next week to tackle the issue.
• Shares of Volskwagen fell as much 2.5% in earlier Frankfurt trading.