EN
The article presents oligopoly models of Cournot, Bertrand and Stackelberg and the use of models to firms' connections modeling. The presented three oligopoly models, despite they have over 150 or almost 100 years, they are still in use. The aim of the article is presentation of horizontal merger model, in which firms have Cournot conjectures and there is also an analysis of relation between merger profitability and a rivalry coefficient.