Article is dedicated to the issue of monopoly, both in theory, as well as practice based on the example of a takeover of T-Mobile US by AT&T. It also contains the analysis of the factors which had influence on putting the transaction on hold by the Federal Communications Commission. The paper presents potential consequences of the acquisition according to the economists, together with the reasoning of the entity
applying for the approval of the transaction. The analysis shows the multidimensional consequences of this type of transaction on development of innovation in the telecommunications market.