TUI merged with First Choice in 2007
Europe's biggest travel firm, TUI Travel, is to take a stake in German airline Air Berlin.
The firm will pay 28.5m euros (£26.5m) for a 19.9% holding in Air Berlin as part of a cross-shareholding agreement.
In return, the German airline will get the same stake in TUI's German carrier TUIfly, expanding Air Berlin's routes in Stuttgart and Italy.
TUI was created in 2007 when the tourism division of German operator TUI AG merged with First Choice.
The deal aims to lower TUI's running costs and reduce the number of flights they run to European destinations, which has been one of its aims since the merger.
As part of the deal, Air Berlin will take on the leases for 17 of the TUIfly aircraft.