1. Member States shall require any natural or legal person or such persons acting in concert (the 'proposed acquirer'), who have taken a decision either to acquire, directly or indirectly, a qualifying holding in an investment firm or to further increase, directly or indirectly, such a qualifying holding in an investment firm as a result of which the proportion of the voting rights or of the capital held would reach or exceed 20 %, 30 % or 50 % or so that the investment firm would become its subsidiary (the 'proposed acquisition'), first to notify in writing the competent authorities of the investment firm in which they are seeking to acquire or increase a qualifying holding, indicating the size of the intended holding and relevant information, as referred to in Article 13(4).