Under the Commission Consolidated Jurisdictional Notice under Council Regulation (EC) No 139/2004 on the control of concentrations between undertakings, sole control is defined as follow : "Sole control is acquired if one undertaking alone can exercise decisive influence on an undertaking. Two general situations in which an undertaking has sole control can be distinguished. First, the solely controlling undertaking enjoys the power to determine the strategic commercial decisions of the other undertaking. This power is typically achieved by the acquisition of a majority of voting rights in a company. Second, a situation also conferring sole control exists where only one shareholder is able to veto strategic decisions in an undertaking, but this shareholder does not have the power, on his own, to impose such decisions (the so-called negative sole control). In these circumstances, a single shareholder possesses the same level of influence as that usually enjoyed by an individual shareholder which jointly- controls a company, i.e. the power to block the adoption of strategic decisions. In contrast to the situation in a jointly controlled company, there are no other shareholders enjoying the same level of influence and the shareholder enjoying negative sole control does not necessarily have to cooperate with specific other shareholders in determining the strategic behaviour of the controlled undertaking. Since this shareholder can produce a deadlock situation, the shareholder acquires decisive influence within the meaning of Article 3(2) and therefore control within the meaning of the Merger Regulation." © European Commission
See also Notion of control