Analyze the relationship between 'Airbus Group' and 'ATR' within the context of the input sentence.
Options: location of formation, platform, owner of, operator

Industry sources have said Airbus Group is exploring increasing its stake in tandem with BAE Systems as part of a wider move that could see Airbus cede its 50 percent share of turboprop maker ATR to its joint-venture partner Finmeccanica.
owner of