The monopolist's optimal R&D portfolio

The monopolist's incentives towards product and process innovations are evaluated against the social optimum. The main findings are that (i) the incentive to invest in cost-reducing R&D is inversely related to the number of varieties being supplied at equilibrium, under both regimes; (ii) distortions obtain under monopoly, w.r.t. both the number of varieties and the technology. With substitutes, the monopolist's product range is smaller than under social planning, while with complements the product range is the same under both regimes. For any given number of goods, the monopolist operates at a higher marginal cost than the planner does.