‘Vertically integrated undertaking’ in the European Union Internal Electricity Market means an electricity undertaking or a group of electricity undertakings where the same person or the same persons are entitled, directly or indirectly, to exercise control, and where the undertaking or group of undertakings perform at least one of the functions of transmission or distribution, and at least one of the functions of generation or supply of electricity (Article 2(21) of the Directive 2009/72/EC of the European Parliament and of the Council of 13 July 2009 concerning common rules for the internal market in electricity and repealing Directive 2003/54/EC).
Article 2(34) of the said Directive contains, moreover, the definition of ‘control’, which means rights, contracts or any other means which, either separately or in combination and having regard to the considerations of fact or law involved, confer the possibility of exercising decisive influence on an undertaking, particularly by:
(a) ownership or the right to use all or part of the assets of an undertaking;
(b) rights or contracts which confer decisive influence on the composition, voting or decisions of the organs of an undertaking;
Nearly identical definitions are in, respectively, Article 2(53) and 2(56) of Directive (EU) 2019/944 of the European Parliament and of the Council of 5 June 2019 on common rules for the internal market for electricity and amending Directive 2012/27/EU.