Interesting article in the economist on the airline industry. For starters, the industry is loosely divided into 3 groups:
a) Skyteam - AirFrance, Delta Airlines, KLM??
b) Star - Luftansa, United Airlines, Singapore
c) oneWorld - BA, American, Cathay Pacific
(Pooling of flights, coordinating schedules, prices are the kind of functions these loose 'alliances' perform).
Airlines are deeply controlled by national governments and actually ban cross-border mergers. ( Also within their countries also, they cant consolidate as they can bring anti-trust laws because of dominant controlling hubs). So the industry is trying to get around these by having symbolic stakes as the above to consolidate.