External growth strategies face crucial barriers when taken into consideration for investing if the involved companies are not audited. The integrity of a company’s financial information, its control systems, and its sustainable behavior represent cornerstones when participating in mergers and acquisitions (henceforth M&As). Thus, the audit function became a must and its role increased over the years, becoming an intrinsic part of faithfully disclosing financial and nonfinancial information (sustainable reporting included). M&As are ideal when the need for rapid innovation is required, in order to maintain or develop a sustainability policy. Given the environmental issues, we analyzed a sample of 1491 target companies listed on Bucharest Stock Exchange, clustered into three categories: polluters, medium polluters, and low polluters. The study reveals that the investors’ decision to purchase a certain amount of stake in target companies is influenced by the audit opinion and the sector in which they operate, depending on their pollution status.