Source: European Parliament
Article 345 of the Treaty on the Functioning of the European Union (TFEU) stipulates that the Treaties shall in no way prejudice the rules in Member States governing the system of property ownership. Hence, Member States may for instance act as economic operators and invest in and control companies.
The rules for the control exercised over a company by a Member State based on its shareholding in that company, are then set by the relevant national corporate law provisions of each Member State.
On that basis, each Member State has the right to act as a shareholder in a company, to the extent the exercise of such shareholding rights is in line with the relevant national corporate law and does not infringe relevant provisions of EU law, such as Article 106 TFEU (concerning possible special and exclusive rights) or Article 107 TFEU (concerning possible state aid).