PI 3.10 Market Structure Measurement. In 2005, Federated Department Stores, Inc., proposed to acquire The May Department Stores Co., thereby combining the two largest chains in the USA of so-called traditional or conventional department stores. Conventional department stores typically anchor enclosed shopping malls, feature products in the midrange of price and quality, and sell a wide range of products. The proposed transaction would create high levels of concentration among conventional department stores in many metropolitan areas of the USA, and the merged firm would become the only conventional department store at certain of the 1200 malls in the USA.