  We study a spatially homogeneous model of a market where several agents or
companies compete for a wealth resource. In analogy with ecological systems the
simplest case of such models shows a kind of "competitive exclusion" principle.
However, the inclusion of terms corresponding for instance to "company
efficiency" or to (ecological) "intracompetition" shows that, if the associated
parameter overcome certain threshold values, the meaning of "strong" and "weak"
companies should be redefined. Also, by adequately adjusting such a parameter,
a company can induce the "extinction" of one or more of its competitors.
