Ferdinand Piech resigned as chairman of Volkswagen over the weekend. The cause: reneging on a deal to support CEO Martin Winterkorn, and secretly plotting to oust him instead, according to sources close to the VW board. When the company's works council, and Lower Saxony — the company's top shareholder — heard that Piech had been lobbying family members behind the scenes to install Matthias Mueller, the CEO of Porsche, as the head of VW, they demanded a meeting of the board.