Over the last decades, Mergers and Acquisitions (M&A) have become key strategic alternatives to organic growth, enabling firms to expand in new geographies, broaden their product or service portfolios, increase their market power or diversify their business activities, for instance. Historically, although M&A deals have occurred in cyclical patterns, the number of transactions as well the total amount invested have followed an increasing trend. For instance, in 2021, the number of M&A deals conducted worldwide even peaked at an absolute record of 63,215 deals, for a total amount of $5,800 billion, comparable to the annual GDP of a country like Japan. Although the literature on M&A is vast and multi-disciplinarian, the performance of such transactions as well as their influencing factors have remained debated issues. This paper-based dissertation investigates the implications of corporate social responsibility (CSR) on financial markets’ anticipations in the context of M&A announcements. The first manuscript (Manuscript A) corresponds to a literature review on the determinants to financial markets’ reactions around M&A announcements. The second manuscript (Manuscript B) investigates the impact of both acquirers- and targets’ CSR engagements as well as their CSR profiles distance on synergetic gains anticipated by financial markets around M&A announcements. The third manuscript (Manuscript C) focuses on the impact of acquiring firms’ CSR engagement on the accuracy of financial markets’ anticipations with regards to the long-term operating performance of M&A deals. The fourth manuscript (Manuscript D) analyses whether acquirers’ CSR performance impacts M&A premia, since the premia offered to target shareholders contain acquiring managements’ anticipations regarding potential synergetic gains and are by the way critical to the deals’ value creation processes.