The subject of the final paper is one of the forms of the dominant market structure - oligopoly. An oligopoly is a form of imperfect competition, i.e., a market structure that includes a small number of a large number of companies that have a share in the overall market and are mutually dependent on each other. The primary idea behind an oligopolistic market (oligopoly) is that a few companies dominate a particular market or industry, offering similar goods and services. Due to the limited number of players in the oligopolistic market, competition is limited which allows companies to operate successfully. The products that companies in the oligopolistic market produce can be homogeneous or differentiated, and when companies decide on the price of the product and the quantity of the product, they will produce they always take into account the decisions and behavior of the competition on the market. Companies in an oligopolistic market often join to achieve higher profits or to prevent new competitors from entering the market. Given the small number of strong companies in the oligopolistic market and the relationship between them, as well as the fact that there are barriers to entry and exit from the oligopolistic market, companies are often demotivated to enter the oligopolistic market. When it comes to achieving market equilibrium, short-term and long-term, in an oligopolistic market, both in the short and long term, companies in an oligopolistic market tend to make a profit. In addition to the fact that companies in an oligopolistic market can make a profit, they can also operate at a loss or be at a positive zero, which happens when companies have equally high revenues and expenses in business.