This article shows how research on the social structure of markets may contribute to the analysis the growing income inequality in contemporary capitalist economies. The author proposes a theoretical link between embeddedness and social stratification by discussing the role of institutions and networks in markets for the distribution of economic profits between firms. The author claims that we must understand profit and free competition as opposites, as economic theory does. In the main part of the article the author illustrates six typical mechanisms of rent extraction from networks or formal and symbolic rules that embed markets. They emerge from material as well as symbolical access to and influence on the orientation of other market actors. Social structures in markets lead to unequal chances for rent extraction, even if actors produce them for coordination rather than for accumulation purposes. This is how market sociology and theory of capitalism can be linked more closely.