19.—(1) A merger or acquisition to which paragraph (a) or (b) of section 18(1) applies, or which is referred to in subsection (3) of section 18 and has been notified to the Authority in accordance with that subsection, shall not be put into effect until—

(a) subject to subsection (3), the Authority, in pursuance of section 21 or 22, has determined that the merger or acquisition may be put into effect, or

(b) the Authority has made a conditional determination in relation to the merger or acquisition, or

(c) subject to subsection (4), the period specified in subsection (2) of section 21 has elapsed without the Authority having informed the undertakings which made the notification concerned of the determination (if any) it has made under paragraph (a) or (b) of that subsection (2), or

(d) subject to subsection (5), F43[120 working days after the appropriate date have elapsed, or, where a requirement was made under section 20(2), 120 working days and any period of suspension that applied pursuant to section 22(4A) after the appropriate date have elapsed] without the Authority having made a determination under section 22 in relation to the merger or acquisition,

whichever first occurs.

(2) Any such merger or acquisition which purports to be put into effect, where that putting into effect contravenes subsection (1), is void.

(3) Notwithstanding subsection (1)(a), the determination referred to in that provision shall not operate to permit the merger or acquisition concerned to be put into effect if the merger or acquisition is not put into effect before the expiry of the period of 12 months after the date on which the determination is made.

(4) Notwithstanding subsection (1)(c), the failure by the Authority to inform the undertakings concerned of the matter referred to in that provision shall not operate to permit the merger or acquisition concerned to be put into effect if the merger or acquisition is not put into effect before the expiry of the period of 13 months after the appropriate date.

(5) Notwithstanding subsection (1)(d), the absence of a determination by the Authority in the circumstances referred to in that provision shall not operate to permit the merger or acquisition concerned to be put into effect if the merger or acquisition is not put into effect before the expiry of the period of F43[12 months after the relevant period referred to in subsection (1)(d) has elapsed].

(6) In this section “appropriate date” means—

F44[(a) unless paragraph (b) applies, the date of receipt by the Commission of the notification of the merger or acquisition concerned under section 18(1),

(aa) notwithstanding subsection (8), and unless paragraph (b) applies, the date of receipt by the Commission of the first notification of a merger or acquisition under section 18(3),]

(b) if the Authority has, under section 20(2), made, within F43[30 working days] from the date of receipt by it of the notification of the merger or acquisition concerned under section 18, a requirement or requirements of one or more of the undertakings concerned—

(i) the date on which the requirement is complied with or, in case 2 or more requirements are made and each is complied with, whichever of the dates on which the requirements are complied with is the later or latest,

(ii) where the requirement is not complied with or each of the 2 or more requirements is not complied with, the date immediately following the expiry of the period specified in the requirement or, as the case may be, the date immediately following the expiry of whichever of the respective periods specified in the requirements is the last to expire, or

(iii) in case 2 or more requirements are made but one or more but not all of them are complied with, the later or latest of the following dates, namely the dates provided by applying—

(I) subparagraph (i) to the requirement or requirements complied with, and

(II) subparagraph (ii) to the requirement or requirements not complied with.

F43[(7) The reference, in the definition of ‘appropriate date’ in subsection (6), and in section 22(4A), to the period specified in a requirement, is a reference to—

(a) the period specified in the requirement as being the period within which the information concerned shall be supplied, and

(b) where a requirement has been extended under section 20(2A) or section 20(2B), the date specified in the requirement as so extended. ]

(8) For the purpose of the reference in subsection (6), and in any other provision of this Act, to the date on which the Authority receives a notification under section 18, if a single notification is not made by all the undertakings concerned, the said reference shall be construed as a reference to the later or latest of the dates on which a notification of the merger or acquisition concerned under section 18 is received by the Authority.

(9) Subsection (8) is without prejudice to section 18(14).