The FCC created this tool to help identify markets where cross-ownership limits should be retained. The index was based on the Herfindahl-Hirschman Index (HHI), which is used by the Federal Trade Commission and Department of Justice to measure market concentration. It is commonly used to assess a merger's effect on competition in a market. HHI is calculated by summing the squares of each firm's share of a given market. Therefore, a highly competitive market will have a lower score. Included in the Diversity Index are broadcast television, newspapers, radio, and internet. Based purely on popularity of each media source, the FCC assigned broadcast TV 33.8%, newspapers 20.2%, weekly periodicals 8.6%, radio 24.9%, cable internet 2.3%, and all other internet 10.2%. Within each media type, the number of outlets were assigned an equal market share. The summation of all media types for each owner was then squared and added to the index. Scores were determined for all markets with five or fewer television stations, all markets with 15 to 20 television stations, and ten randomly selected markets with between six and ten stations. The FCC then considered what would happen to scores under different ownership limit scenarios. In small sized markets, scores dramatically increased, showing the need for greater control. Due to events of the eventual court case, the Diversity Index never went into effect.