Ryanair, Europe's biggest budget airline, launched a shock bid for Aer Lingus on Thursday, valuing the former Irish state carrier - which listed just four days ago - at 1.48 billion euros ($1.9 billion).
Aer Lingus' board rejected the offer, saying it undervalued the group's business and long-term growth potential. Aer Lingus, which made a formal market debut in Dublin and London on Monday, priced its initial public offering last week at 2.20 euros.
"This offer represents a unique opportunity to form one strong airline group for Ireland and for European consumers," Ryanair Chief Executive Michael O'Leary said.
Under the deal, Ryanair - which previously said it had no interest in the long-haul market - and Aer Lingus, a short and long-haul carrier, would be run separately. Ryanair would stick to its highly successful low-cost, European carrier model.