In the Cartesio decision of December 2008, the European Court of Justice has legitimated the real seat theory for those Member States that require the presence of the administrative seat and the statutory seat in their territories as a condition for a company's valid formation. The Court, by an obiter dictum, has also put forward the idea that the transnational conversion is included in the freedom of establishment of Articles 43 and 48 as a form of international mobility. This article analyses the possible consequences of the Court's decision for regulatory competition in company law in Europe, taking into consideration both aspects.