Abstract
Contrary to their considerable growth in terms of number and value, the operations of mergers and acquisitions reveals, for more than one operation out of two, a failure from the economic and organizational point of view (McKinsey 2000; Mercer Consulting 2001, 2003). The insufficiency of the reasons presented to explain the failures of mergers and acquisitions were largely recognized. The strategic complementarity, although necessary, is not sufficient to carry out expected synergies of such an operation. The human, cultural and informational aspects from now on are used more and more to explain the results (Schweiger & Walsh 1990). It is established today that a great part of the failures is explained by integration difficulties of the methods, management processes and information systems. Thus, the integration stage, once acquisition or merger has been officialised, is the genuine key of success of the operation (Haspelagh and Jemison 1991).
