The subject of the study presented in this article is the process of formation of the price in mergers and acquisitions. Due to the huge number of factors that influence the result of such transactions, the problem of choosing variables for modeling is a difficult task. In order to solve this problem, two stages of the study are distinguished: the choice of the resulting variable and determining the combination of factors influencing it. As a result of a large number of iterations, the main groups of variables, the significance of which was established, has included the indicators of the target company, the indicators of the acquirer company, the duration of the stages of the deal, the parameters of the external environment represented by the interest rate and the index of political risks and vulnerabilities, as well as the types of corporate strategies used by the companies to plan transactions. Particular attention has been paid to the choice of the most significant regression indicator in terms of the adjusted coefficient of determination, reflecting the size of the company's assets.