The American Airlines merger with US Airways is under fire. The reason is simple: a merger between these two airlines would create the largest airline in the world — an airline that would have the potential to monopolize the air travel industry. The Justice Department, as well as several states, have filed a joint lawsuit in order to halt the merger. According to USA Today, the Justice Department noted that a merger between these two airlines would give the merged airline control over a whopping 69% of departure and arrival slots at Washington Reagan National Airport — that would be six times more control over the air activity of that airport than the closest competitor.
While other airline mergers have been successfully executed (United/Continental, Southwest/AirTran, Delta/Northwest), it seems as though the root of the problem with this particular merger is that it would be too big, perhaps too big to fail. It should be noted, however, that a USA Today article from December 2012 reported that despite gloomy speculations, none of the previous airline mergers raised fares as predicted.