Shares in Aer Lingus jumped by 10% on its first day of trading on the stock market.
The company was floated on stock exchanges in Dublin and London at 8am this morning.
The shares were floated at €2.20 and traded at €2.38 at 12.45pm.
The company, which joined the stock market at €1bn, is now valued at well over €1.1bn.
The Government has retained a 28% stake in the airline's privatisation.
It will get €200 million in cash from the deal.
At 1.45am this morning, the Government, Aer Lingus and its bankers hammered out the final details of the flotation of the airline.
The company will get €534m which will help it raise money for a new fleet of aircraft.
Originally the company said it would float at between €2.10 and €2.70. The final price agreed was in the lower part of that range, at €2.20.
It is believed there has been strong demand for the shares from financial institutions and that pension funds are willing to buy into the airline, but not at high prices.
3% of the Government's shareholding is set aside to go to staff in a profit-sharing arrangement.
