The market structure in the marketing of banana export type produced in the department of Magdalena historically has been imperfect, with multinational marketers who will determine the quantities of bananas they buy from the producers or the price, generating a loss of social welfare to banana producers. In the present study measured the degree of market concentration by marketers across the Herfindahl concentration index-Heirschman (HHI), then through econometric time series proceeded to show the relationship between the prices paid to producers and the concentration index (HHI), finally using the model of Cournot and Stackelberg, from the econometric estimation of an inverse function of supply and application of pure strategies in noncooperative games empirically tested strategies marketers are doing.