Merger policy.

wPost-merger HHI below 1,000.

nUnconcentrated.

nRespond with Sherman 1 if explicit collusion.

nNo challenge to mergers in this region.

w Post-merger HHI between 1,000 and 1,800.

nGray area.

nAgencies unlikely to challenge a merger increasing HHI by less than 100 points, but likely to challenge otherwise unless agencies think the merger won't lessen competition.

wPost-merger HHI above 1,800.

nHighly concentrated.

nChallenge if change in HHI > 50, unless agencies think merger won't lessen competition.

DOJ-FTC Horizontal Merger Guidelines.