Existe-t-il une structure optimale de la propriété des firmes en termes de profit ?

The possible existence of a link between the structure of firms' equity and profitability is a recurrent question among economists. The primary objective of this article is to provide a critical analysis of the two most recent hypotheses on the subject, one put forward by Demsetz, and the other by Morck, Schleifer, and Vishny. Although frequently quoted and regarded as self-evident, on analysis both turn out to be very unconvincing. The second objective is to present our own thesis on the subject of the link between capital structure and profitability. Empirical studies have shown the neutrality of capital structure in this respect, and we propose an interpretation based on an approach very far removed from that posited by the agency theory.