Durable goods oligopoly

This paper models a durable-goods oligopoly as a differential game. Two cases are treated: sales, where firms cannot lease but must sell the good in question, and leasing, where firms do not sell but only rent. In the sales case, firms face increasing marginal cost of production and the good in question depreciates. For this case, a rational expectations feedback Nash equilibrium is constructed for which monopoly or oligopoly output is less than the efficient level. This gap between oligopoly and competitive output diminishes as the number of firms increases. When firms can only lease the good, the good is assumed not to depreciate and the monopoly level of steady state output is compared with the level of steady state output for a feedback equilibrium duopoly. For this case, the duopoly equilibrium has steady-state output that is less than the corresponding efficient level, but greater than the monopoly level. The leasing model is shown to be isomorphic to the adjustment-cost duopoly model of Driskill and McCafferty (Journal of Economic Theory, 49 (1989) 324–338).