The impact of the economic consequences of decisions in the field of concentrations explains the specificity of the control procedure defined by the Regulation No 139/2004 and Procedural Regulation No 2004 802/2004 supplementing it. The control as instituted is a prior control subject to extremely short deadlines and carried out by an administrative body, the Commission, acting under the supervision of the EU courts. For a uniform application of EU law, the Commission has exclusive jurisdiction to implement Regulation No 139/2004 subject to the civil consequences where national laws apply, as for restrictive agreements and abuse of dominant position. All concentrations which exceed certain thresholds must be notified to the EU authorities and must be suspended pending the Commission’s decision, which in principle cannot be taken more than five months after notification of the transaction.

Furthermore, the procedure is only initiated following a preliminary examination (phase I) after which in most cases the procedure is closed. An in-depth (phase II) examination is reserved for transactions that raise serious doubts as to their compatibility with the internal market. Finally, an informal procedure may take place prior to the formal procedure, with the Commission encouraging undertakings to take part in informal and confidential discussions with its representatives prior to notification, in order to verify that the proposed transaction does indeed fall within the scope of the regulation and possibly lighten the notification file that undertakings must submit.