The Office of Fair Trading (OFT) is investigating Ryanair Holding plc’s acquisition of a 29.82 per cent shareholding in Aer Lingus Group plc. The investigation follows the General Court’s decision that individual Member States may apply national competition law to Ryanair’s stake in the company. Ryanair first acquired its shareholding in the Irish flag carrier in late 2006. One of the issues under consideration is whether the OFT is acting outside the four month timeframe for merger review, as stipulated in the Enterprise Act 2002 (the Act). The OFT intends to assess whether the acquisition qualifies as a ‘relevant merger situation’ on the basis that Ryanair is able to materially influence the behaviour and policy of Aer Lingus. Whether it does qualify as a merger, the OFT will consider if the acquisition raises competition issues under the ‘substantial lessening of competition’ test.