Taking the early U.S. automobile industry as an example, we evaluate two competing hypotheses on geographic concentration of industry: local externalities versus employee spinoffs. Our findings suggest that both forces contribute to industry agglomeration through their specific channels, and the...

We develop a "passive learning" model of firm entry by spin-off: firm employees leave their employer and create a new firm when (a) they learn they are good entrepreneurs (type I spin-offs) or (b) they learn their employer's prospects are bad (type II spin-offs). Our theory predicts a high...

Taking the early U.S. automobile industry as an example, we evaluate four competing hypotheses on regional industry agglomeration: intra-industry local externalities, inter-industry local externalities, employee spinouts, and location fixed-effects. Our findings suggest that inter-industry...

This paper explains why payment card companies charge consumers and merchants fees which are proportional to the transaction values instead of charging a fixed per-transaction fee. Our theory shows that, even in the absence of any cost considerations, card companies earn much higher profit when...

This paper provides a new theory for two-sided payment card markets by positing better microfoundations. Adopting payment cards by consumers and merchants requires a fixed cost, but yields lower marginal costs of making payments. Considering this together with the heterogeneity of consumer...

How should a monopolist price a durable good or a new technology that is subject to network externalities? In particular, should the monopolist set a low "introductory price" to attract a "critical mass" of adopters? In this paper, we provide intuition as to when and why introductory pricing...

I discuss various properties of the equilibrium, including the pricing function, the system's expected motion, and the stationary distribution of market shares. I derive several results analytically. I then confirm and extend these results by numerical computation. Finally, I use the model to...