Abstract: Developed in modern conditions, such a new form of enterprise reorganization as mergers and acquisitions has many positive aspects for business, including savings on resources, market share growth and much more. However, not all mergers and acquisitions have high efficiency, some of them are unsuccessful. The reason for this is a variety of factors affecting the effectiveness of influence and acquisition transactions. This article is devoted to the study of these factors. The author discusses the essence and main characteristics of mergers and acquisitions. The dynamics of the volume and territorial representation of mergers and acquisitions in the world in 2015-2022 are analyzed. On the basis of foreign and domestic experience, the author identified and systematized factors that influence the level of efficiency of mergers and acquisitions and contribute to its improvement. The author identified two groups of factors contributing to the greatest efficiency of mergers and acquisitions: factors of efficiency improvement at the initial stage; factors of efficiency improvement at the stage of implementation and subsequent transaction support. Detailed study and planning of the factors included in these groups will contribute to the most effective implementation of the mergers and acquisitions transaction, as well as increase its efficiency in the future.