In the 1950s and 60s, Japanese and US antitrust authorities occassionally used the degree of concentration to regulate industries. Does regulating firms based on their market shares make theoretical sense? We set up a simple duopoly model with stochastic R&D activities to evaluate market share...

In the 1950s and 60s, Japanese and US antitrust authorities occassionally used the degree of concentration to regulate industries. Does regulating firms based on their market shares make theoretical sense? We set up a simple duopoly model with stochastic R&D activities to evaluate market share...

We prove the existence of stationary equilibrium in the primary and secondhand markets for an indivisible consumer durable in a general model with stochastic degradation and endogenous scrappage decisions.