When considering the challenges for sustainable business, companies implementing cross-border reallocation of capital by means of mergers and acquisitions should take into account the context and evaluation of attributes of their future implementation. The main aim of the paper is, therefore, to identify and specify the key attributes of sustainable cross-border mergers or acquisitions (M&As) influencing the considerations about their future implementation. On the basis of the views of managers from 120 companies (international corporations selected from the Zephyr database) located in 45 countries within the European area that had previously been the subject of a cross-border merger or acquisition, significant attributes were extracted in connection with their experience from their implementation. These attributes are taken into account when considering the implementation of a cross-border merger or acquisition in the future. A factor analysis of the data obtained allowed the extraction of three key attributes of implementation of a potential merger and acquisition process as an important tool of business sustainability—aims, concerns, and reasons. This paper further presents the basic parameters of the Attributes of Future Mergers and Acquisitions (AFM&A) methodology: eigenvalues, Cronbach’s alpha values, the percentage of the variance explained, inter-correlations of the extracted factors, and the results of an analysis of differences in the assessment of the extracted factors by managers. At the same time, no statistically significant differences were found in the assessment of the extracted merger and acquisition assessment factors. The study fills in the research gap in the area by identifying and specifying the attributes of considering the future implementation of M&A management in terms of the broader concept of this issue.