First mover advantage in a dynamic duopoly with spillover

We present a dynamic duopoly model of technical innovation where R&D costs decrease exogenously with time, and inter-firm knowledge spillover lowers the second comer's R&D cost. The spillover effect only becomes available after a disclosure lag. These features allow us to identify a new type of equilibrium: the leader delays investment until the R&D cost is low enough that the follower finds it optimal to invest as soon as he can benefit from the spillover. This equilibrium is subgame perfect over a wide range of parameters, and raises several interesting implications. First, in our new equilibrium the time delay between the two R&D investments is realistically short. Second, while the presence of a spillover favors the second mover, this benefit is not enough to rule out a first mover advantage. Indeed, the first mover advantage survives whenever technical progress is sufficiently fast and the disclosure lag is relatively long. Third, in case of a major innovation our equilibrium implies under--investment, which requires a substantial public intervention in favour of the investment activity.