Persistence of monopoly and research specialization

We examine the persistence of monopolies in markets with innovations when the outcome of research is uncertain. We show that for low success probabilities of research, the incumbent can seldom preempt the potential entrant. Then the efficiency effect outweighs the replacement effect. It is vice versa for high probabilities. Moreover, the incumbent specializes in safe" research and the potential entrant in risky" research. We also show that the probability of entry has an inverted U-shape in the success probability. Since even at the peak entry is rather unlikely, the persistence of the monopoly is high.