The private equity firms Axa and Permira are buying the online travel agent Opodo for €500m (£424m) from the Spanish travel reservations group Amadeus.
Following the acquisition, Axa and Permira plan to merge Opodo with their two rival online travel firms, the French Go Voyages and Spain's eDream.
Opodo, which was set up in 2001 by a consortium of European airlines including British Airways, Air France, KLM and Iberia, is based in the UK and operates websites across Europe.
Rival private equity firms BC Partners and Cinven floated Amadeus last April.
Air France, Iberia and Lufthansa still own minority stakes in the business.