Oligopolists There are four market structures in our economy today : Perfect competition, monopolistic competition, oligopolies and monopolies. This essay shall describe the oligopoly market. The definition of an oligopoly states that in an industry, a small number of firms dominate the market. There are a low number of firms in the industry, becasue and adding to the barriers to entry. The barriers of entry to an oligopolistc market include the financial resources needed to enter and such regulations from the government or patents. In this market, there is a high degree of differentiated products, and so with all of the above factors combined in this market,