There is no term " Ologopolios " by what the consultant must refer to " oligopolies " word of Greek origin formed by OLIGO 40 concepts;FEW ) and SHEAVES (SELLERS ) by which means oligopolies are few vendors do ( or offering ). In a market oligopoly, occurs when it is dominated by a small number of producers, suppliers, which allows them to prevent others from entering the market, and even be able to collude to determine prices through freedom of choice in buying one or another bidder, positively discriminating for price, quality or other characteristics or conditions, which tended to free competition, and all this at the expense of consumers, who lose the ability to option and therefore the market can regulate themselves. The existence of oligopolies is required in some areas, therefore, must be properly regulated and controlled, in order to prevent externalities that impede the proper functioning of the market and its self-regulation.Areas of oligopolies, basic services talkes as service water, electricity, etc. In Chile there is an oligopoly in the field pharmacies, with 3 chains that dominate the market, producing what is called " the form " in the fixing of prices, i.e. chain that dominates fixed prices, and two other chains are suited to them, which makes it difficult to determine when they are competing and when you are entering.Finally, the existence of oligopoly does not imply necessarily that there are no other bidders, but they usually do not attain important dimensions of the market, and product of oligopoly, it is difficult to be able to cease to be a small supplier, with low marginalization in products.