Last I looked, maybe year-old data, UA had 45% vs. 40% for AA+US. Haven't looked at the stats in depth, but it sure seemed like virtually every route I flew on UA had its capacity dropped post-merger: 747s>777s, 777s>763s, 763s>739s, etc. I haven't seen this happening at AA here, leading to my expectation that their market shares will reverse over the next few years. If you'd like to point me to some good data that shows otherwise, I'm willing to be convinced. Either way, this is certainly not the kind of fortress hub that UA seems to prefer these days, where passengers have no real alternative.