The changes are in the Herfindahl-Hirschman Index scores for the merger and for individual routes.
Here’s the lawsuit’s explanation of the HHI:
· Concentration in relevant markets is typically measured by the Herfindahl-Hirschman Index (“HHI”).
· Markets in which the HHI exceeds 2,500 points are considered highly concentrated. Post-merger increases in HHI of more than 200 points are considered to be significant increases in concentration.
· In more than 1,000 of the city pair markets in which American and US Airways currently compete head-to-head, the post-merger HHI would exceed 2,500 points and the merger would increase the HHI by more than 200 points. For example, on the Charlotte-Dallas city pair, the post-merger HHI will increase by 4,653 to 9,324 (out of 10,000).
· The original complaint put the change in HHI on the DFW-CLT route at 4,648, climbing to 9,319. Small difference, but a difference.
The amended complaint lists the change in HHI for 1,008 routes. The original complaint listed the change in HHI for 1,043 routes. Those routes are “city pairs where the merger is presumptively illegal.” The original list included routes that the revised list has dropped. The revised list has routes that the original list did not.
Rich Parker's response is due September 10th. They will likely settle this just prior to the trial date.