GameStop Racks Up the Points No retailer has more cachet among gamers than GameStop. For now, only Wal-Mart has a larger market share—21.3% last year. GameStop’s share was 21.1% last year, and may well overtake Wal-

Mart this year. But if new women gamers prefer shopping at Target to GameStop, Wal-Mart and Target might erode GameStop’s market share.

a. According to the news clip, what is the structure of the U.S. retail video-game market?

b. Estimate a range for the four-firm concentration ratio and the HHI for the game market in the United States based on the information provided in this news clip.