The Emergence of Market Structure
研究场外交易中交易者投资联系技术并参与双边交易，发现均衡和最优配置中涌现出丰富的市场结构，包括连续异质性和中间商，并探讨了外部性导致的过度投资及福利改进政策。
Abstract We study a model of over-the-counter trading in which ex ante identical traders invest in a contact technology and participate in bilateral trade. We show that a rich market structure emerges both in equilibrium and in an optimal allocation. There is continuous heterogeneity in market access under weak regularity conditions. If the cost per contact is constant, heterogeneity is governed by a power law and there are middlemen, market participants with unboundedly high contact rates who account for a positive fraction of meetings. Externalities lead to overinvestment in equilibrium, and policies that reduce investment in the contact technology can improve welfare. We relate our findings to important features of real-world trading networks.