We study the nature of market competition in relation to stability of collusion in the infinitely repeated play of a two-stage game of product innovation and market competition, and show that cooperation in giving R&D efforts is more easily sustained when firms compete in quantity than in price.

We address two questions. First, does the excess entry result of pure oligopoly hold when firms face a substitute good produced by a public firm? Second, what would be the optimal ownership of the public firm? We find that excess entry still occurs, but the excessiveness is largely mitigated due...