The FTC allows monopolies in circumstances also where the cost of competing infrastructures are impractical. The cable companies have regional monopolies because they would either have to allow a competitor to use their cables or the competitor would have to run their own (the local governments would not allow that). Phone company, water, power, etc... all legal monopolies. The cost of launching a satellite is huge. The usable orbit space is finite. You can't just throw another satellite over the equator because that space is already taken. It really doesn't make sense for there to be two satellite radio companies any more than it makes sense for there to be two water companies somewhere. By allowing them to merge, their costs go down and the service price should remain stable for the consumer for quite some time.