Abstract: The growing popularity of mergers and acquisitions is due to their proven effectiveness in practice, which is expressed not only in the possible improvement of economic indicators, but also in the possibility of combining resources, knowledge and experience, increasing competitiveness, increasing innovation, reducing risks and other scale effects. However, during mergers and acquisitions, companies participating in such transactions face cost management problems, which often reduces their effectiveness and negatively affects the performance of further activities of participating companies up to record losses. The research goal is to identify, based on the analysis of foreign and Russian experience, the factors that form the problems of managing the value of companies as a result of the implementation of mergers and acquisitions. The objectives of the study are: to consider the concept and essence of mergers and acquisitions, their advantages and disadvantages in modern economic conditions; to analyze foreign and Russian experience in managing the value of companies as a result of mergers and acquisitions; to identify factors that form the problems of managing the value of companies as a result of mergers and acquisitions. The problems of managing the value of companies as a result of the implementation of mergers and acquisitions are caused by many factors. The article presents the concept and essence of mergers and acquisitions, their advantages and disadvantages in modern economic conditions. The most vivid foreign and Russian experience of managing the value of companies as a result of mergers and acquisitions is analyzed, trends and problems existing in this area are identified. According to the results of the study, the factors that form the problems of managing the value of companies as a result of the implementation of mergers and acquisitions were identified.