This paper proposes to analyze the correlation between the reputation of the investment banks, and the quality of the services offered by the latter as advisors in an M&A operation. It starts from an analysis of the literature that shows the general theory concerning M&A operations. Subsequently, the research focuses on the role of the advisor, and therefore of investment banks, with specific reference to the main factors that have led the top financial banks to success. To what extent is it really advantageous to recruit a top investment bank compared to a bank that has a lower reputation? This empirical analysis covers a specific period, whose middle point is to be considered that event, one of the most significant of today's finance, which has distinguished the financial world of recent years: the failure of Lehman Brothers. The analysis focuses, in fact, on the six years preceding the crisis that began precisely following the bankruptcy of Lehman Brothers, and over the six years following this crisis. The answer to this question is exposed after the empirical analysis that pulls the strings of the research and gives a well-founded answer, based on methodologies and analysis, exposing results aimed at demonstrating that the creation of value for the shareholders of the acquirer and target company does not it can be found in the advice offered by the top investment banks. In the statistical research some other variables are found significant for value creation.