In 2015 Delta Air Lines made a $450 million investment in Shanghai-based China Eastern Airlines. That left fellow SkyTeam member Guangzhou-based China Southern Airlines out in the cold. Two years later, American Airlines followed with a $200 million investment (for a 2.76% stake) in Chinese state-controlled China Southern.
China Southern left SkyTeam. They introduced AAdvantage mileage-earning and redmeption and entered into a joint venture with British Airways. BA’s largest shareholder, Qatar Airways, took a 5% stake in China Southern as well.