Shares in Aer Lingus moved lower today as reports that the airline could lose all but four of its landing slots at London's Heathrow airport if Ryanair took full control of it hit market prices.
Shares in the airline fell just under 1 per cent to €1.08 on the Irish market, with Ryanair's stock ticking higher to €4.828.
Ryanair has offered to sell 20 of its rival's 24 landing slots at the UK's busiest airport to British Airways as part of an agreement aimed at allaying the European Commission's concerns over competition if it gives the airline the go-ahead to take over Aer Lingus.
Ryanair, which owns 29.8 per cent of Aer Lingus, renewed its €700 million takeover bid in June, five years after the commission blocked its first attempt.
Its latest bid is more extensive than when the merger was first blocked in 2007, according to the EU competition authority and it faces an uphill battle to win regulatory approval.
In a statement of objections released last month, the European competition authority said the merged carrier would hold a more dominant position than five years ago and would have an effective stranglehold on more than 40 routes.
A determination to change that landscape has prompted Ryanair to seek deals with British Airways and the smaller carrier Flybe. The dramatic overhaul of routes between Ireland and Britain would see as many as six British Airways planes and four from Flybe, based in the Republic.
If it is given the green light by the commission, the proposed deal between Ryanair and International Airlines Group, the parent company of British Airways, would maintain competition on three routes from Ireland into Heathrow at current levels. It would see British Airways take over Aer Lingus services from Cork, Shannon and Dublin and run them as normal for a period of between three and five years.
A separate part of the same takeover process would see Flybe operate flights to and from Ireland on 20 other routes where Ryanair and Aer Lingus currently both have services for at least three years.