A majority stake in Gatwick Airport is to be sold to French operator Vinci Airports for £2.9bn.
Vinci Airports, part of infrastructure group Vinci, will buy 50.01% of the UK's second-busiest airport.
The other 49.99% will be managed by current owners Global Infrastructure Partners (GIP).
The airport was closed in the run-up to Christmas after reports of drone sightings, in what is thought to be the most disruptive incident of its kind.
Flights were grounded and about 140,000 passengers affected over three days during the incident.
In 2016, Gatwick's expansion plans were dealt a blow when the government rejected its proposal for a new second runway while giving the go-ahead for Heathrow to build a third runway.
Gatwick was acquired by a GIP-led consortium in 2009.
More than 45 million passengers travel through Gatwick each year, flying to 230 destinations in 70 countries, according to its website.
The deal would make Gatwick the largest airport in Vinci's network, which will grow to 46 airports in 12 countries - with a total traffic of about 228 million passengers a year, according to the company.
It follows Vinci's takeover of Airports Worldwide's portfolio earlier this year, which included Belfast International and stakes in 12 airports across the US.
Commenting on recent disruption at Gatwick, Nicolas Notebaert, president of Vinci Airports, said he had "every confidence" in the teams currently in place.
"We will of course work with the airport operational team and the existing shareholders to make Gatwick as resilient as it can be in the face of these new risks," he added.
Analysis by Theo Leggett, BBC business correspondent
Before Christmas, Gatwick was in the public eye for all the wrong reasons. It was brought to a standstill and around 1,000 flights were cancelled due to apparent drone activity.
But the fact remains, London's second airport is potentially a lucrative asset. It handles more than 45 million passengers every year and makes hundreds of millions of pounds in profit.
Vinci says it also offers "significant potential for growth". The question is, where will that growth come from? Gatwick is already operating at a high level of efficiency, squeezing the maximum number of landings and takeoffs from its single runway. Its proposal to build a second runway was rejected by the government in 2016.
But it has a back-up idea. Earlier this year, it set out a "masterplan" for the future - which suggested that an emergency standby runway could be expanded and brought into daily use, to increase capacity.
That would certainly be a controversial move - but if it succeeded, there could be major benefits for Vinci. So perhaps the French firm thinks it's worth a gamble.
US-based GIP said it expected the transaction to be completed "by the middle of next year".
The executive team at Gatwick, including chief executive Stewart Wingate, is to be unchanged.