One of the preferred explanations of the current crisis is the sophistication and the weak transparency of financial markets wich would have allowed speculatives behaviors to elude authorities, supervision. This article develops a different view by putting the emphasis on the model of organization of financial systems which is established, since the 1980-90s, on the predominance of micro-prudential supervision schemes following the hypthesis of free market efficiency. We show that this orientation suffers from the fallacy of composition ; the micro-prudential model turns out unsuitable for the management of systemic risks because of the abscence of an automatic bridge between the micro and the macroeconomic levels. The new regulatory environment feeds successive bubbles the recurrent crises of which seem to require a modification of the rules of organization to avoid the forced socialization of the losses of private actors.
