Belfast International Airport has been sold by its Spanish owners to an American operator.
Abertis is selling the airport with a package of other assets to American company ADC & HAS Airports Worldwide.
Airport managing director John Doran said: "We see this as a very positive vote of confidence in Belfast International Airport and look forward to working with the new shareholder to further and significantly develop the potential of this asset."
The airport handled over 4.3 million passengers last year, flying with airlines including easyJet, Jet2.com and United Airlines. ADC & HAC has paid a total of €284m (£244m) for both Belfast airport and Stockholm Skavsta, the rights to operate terminals at Orlando Sanford in Florida and an airport management business in the US.
Abertis would not say how much Belfast International accounted for in the total price.
Abertis said the sale was part of a strategy aimed at making the most of its asset, however, aviation expert Laurie Price said the sale reflected the troubled state of the Spanish economy. He said he hoped the new owner could take a "longer term" view of the airport's potential.
"Belfast International really has been in the jewel in the crown for Abertis as it has been doing relatively well." Belfast International Holdings made a profit of £2.7m in 2012.
"Hopefully somebody might be able to look at this thing and take a longer-term view and try and resolve the difficulty and competition that there is between Belfast City and Belfast International." That competition meant that both airports lost out on trade to Dublin Airport, he said.
And in contrast, the purchase by a US company reflected the improvements in the American economy. The deal still has to be approved by US regulatory authorities and by minority shareholders in the Swedish and Northern Irish airports.
Ali Gayward, head of Northern Ireland for easyJet, said: "As Northern Ireland's largest airline we look forward to working with ADC to continue to make travel easy and affordable to and from Belfast International Airport."
Economist John Simpson said land owned by the airport would increase its overall value as an asset. He said he believed the sale had taken place because the Spanish company "had taken whatever profit it can out of it". He said the new owners could increase landing charges, given that the airport enjoys a monopoly position as it can fly at 24-hours a day, unlike Belfast's City Airport.
The airports sold to ADC & HAS Airports Worldwide had been owned by Abertis since 2005, when the firm joined Aena Internacional to buy the operator TBI. Abertis sold Cardiff Airport to the Welsh government for €61m this year.
London's Luton Airport will be Abertis' only European asset following the deal. Buyer ADC & HAS was formed in 2008 by Airport Development Corporation of Canada and Houston Airport System. ADC & HAS is based in Houston and currently has a stake in airports in Ecuador and Costa Rica.