From a legal point of view, a merger is a legal consolidation of two entities to one, while an acquisition occurs when an entity takes ownership of shares, interests or assets of another entity. From a commercial and economic point of view, both types of transactions generally result in the consolidation of assets and liabilities within a company, and the distinction between a “merger” and an “acquisition” is less clear. A legally structured transaction as an acquisition may result in the activity of one party moving to indirect ownership of the other party`s shareholder, while a legally structured transaction as a merger may grant partial ownership to the shareholders of each party and control of the merged entity. A deal can be characterized as a merger euphemism of equals if the two CEOs agree that a merger is in the best interests of both companies, whereas if the agreement is unfriendly (i.e. if the management of the target company rejects the agreement), it can be considered an “acquisition”. The merger of equals is often a combination of companies of similar size. Since 1990, more than 625 merger transactions have been announced as mergers totalling $2,164.4 billion.  Some of the largest mergers of equals occurred during the bubble dot.com in the late 1990s and 2000: AOL and Time Warner ($164 billion), SmithKline Beecham and Glaxo Wellcome ($75 billion), Citicorp and Travelers Group ($72 billion). The most recent examples of these combinations are DuPont and Dow Chemical ($62 billion) and Praxair and Linde ($35 billion). The companies agreed that they could better meet the objectives of the transaction and more easily address regulatory concerns by accepting two sequential mergers. Despite the objective of improving performance, the results of mergers and acquisitions (M-A) are often disappointing compared to expected or expected results. Numerous empirical studies have shown high rates of failure of research and development contracts.
Studies focus primarily on individual determinants. A book by Thomas Straub (2007) “The Reasons for Frequent Failure in Mergers and Acquisitions” develops a global research framework that compresses different perspectives and promotes an understanding of the factors underlying merger and economics performance. The aim of this study is to help leaders make decisions. The first important step towards this goal is the development of a common framework of reference, including contradictory theoretical hypotheses from different angles. On this basis, it is proposed to put in place a comprehensive framework to better understand the origins of performance in the field of AM and to tackle the problem of fragmentation by integrating the main competing perspectives in the field of studies on DMs. In addition, according to existing literature, the relevant determinants of the company`s performance are deduced from each dimension of the model.