Markets, Bargaining, and Networks with Heterogeneous Agents

The paper proposes an intertemporal model of bargaining among heterogeneous buyers and sellers placed on a bipartite network. First, it characterizes conditions on the network under which its trading restrictions are inessential and the outcome is arbitrage-free. Instead, when the system is segmented in different trading components, we show how these come about and how prices are determined in each of them. Second, we turn to the issue of network endogeneity, focusing on those networks that are Pairwise Stable. Such networks are shown to always exist and be arbitrage-free. In the latter respect, therefore, they satisfy one of the key properties displayed by frictionless markets. We identify, however, a sharp contrast regarding another key feature: Pairwise-Stable networks are generically inefficient if the matching process is genuinely decentralized. This uncovers a fundamental incompatibility between individual incentives and social welfare in endogenous trading networks. We explain that such incompatibility is not only due to buyer/seller heterogeneity but is also caused by the incentives underlying network formation in a trading context.