The US Department of Justice (DOJ) has amended its challenge to the proposed merger of American Airlines and US Airways, reducing the number of city pairs where it claims the deal would significantly increase competition.
The agency removed 35 city pairs after recalculating the Herfindahl-Hirschman Index (HHI) for the markets and added three to its previous list of markets where competition would increase, in an amended complaint filed on 5 September.
The DOJ stands by its position that the deal is anticompetitive and the merged carrier would have a significantly higher concentration in the more than 1,000 markets it lists in the complaint.
Various outside observers have pointed out that the agency's market concentration analysis differs from that of the US Department of Transportation (DOT) by looking at multiple airports in one region as separate markets, for example Los Angeles International and Orange County John Wayne airports are evaluated separately despite being only 58km apart.
American and US Airways have until 10 September to file a response to the complaint, under a schedule set by the US District Court for the District of Columbia.
The state of Michigan also joined the DOJ and attorney generals from Arizona, Florida, Pennsylvania, Tennessee, Texas, Virginia and Washington DC as a plaintiff in the challenge.
"The decision of the attorney general of Michigan to join the Department of Justice does not diminish the strength of our case, nor our determination to complete this transaction and deliver the benefits of the combination to the customers and communities we serve," say American and US Airways in a joint statement. "We look forward to our day in court."