Abstract: The development of the company via the procedure of Mergers and Acquisitions (M&A) can have the negative impact on its appreciation by business groups, analytics and investors and it can be estimated as value destruction. This problem is relevant today because each diversified corporate structure (the diversified company) is a unique phenomenon. Therefore for the diversified companies, developing by the M&A strategy, the question about value creation or destruction and the market perception of their corporate conception demand to be studied in the framework of the individual approach. This study deals with an analysis of the M&A strategy utilized by Unilever Group, as well as with issues relating to identifying the factors defining the value of a diversified company. To these ends, there are particular methods that can be applied to Unilever Group. Because the structure of this diversified company is rather complex, it makes sense to determine whether the company has been accurately valued by the market (if it is overvalued/undervalued), as well as to define the way the market responds to M&A transactions effected by this company. This study includes an estimation of the effectiveness of Unilever Group’s mergers and acquisitions strategy, aimed at creating the optimum business portfolio within the diversified corporate structure (company) by how it affects value of the company. The general hypothesis assumes that diversification does not have a destructive effect on the value of an international multi-business company that builds its portfolio based on the success of certain brands and business areas.