It is true that XM and Sirius are competitors, and through a merger, consumers will go from having two satellite radio stations to one. Traditionally, anti-trust provisions kick-in when a reduction in consumer choice would lead to less consumer welfare. It can be difficult, though, to determine what the "market" to compare is. While it is true that, post-merger, consumers will now only have a single choice in the satellite radio world, they still have plenty of non-satellite choices. Non-satellite radio is probably a close enough substitute to satellite radio for the merger to pass regulatory muster.