* The new technologies;
* The modification of the demand or a new demand;
* The occurrence of a new segment;
* The changes in the costs or the availability of means of production;
* The changes in the regulation.
As a matter of fact, the creation of a competitive advantage is a tough task, but preserving it is much harder. The preservation of a competitive advantage depends on three conditions. One depends on the sources of the advantage: There is a hierarchy among the advantages, which can be minor (costs reduction of the work force), or major (possession of a special technology whose obtaining requires a higher skill level. The second determining factor is the number of sources of competitive advantage (the more, the better). The third factor of preservation is related to the continuous effort of modernising and perfecting: every advantage is virtually susceptible of being copied. Then the preservation of the competitive advantage requires the firm to adopt an anti-natural behaviour consisting of keeping changing their strategies (naturally no one would change a winning team).