Multiproduct Monopoly Made Simple

Apr 2019 |

Authors: Mark Armstrong,John Vickers

We present a tractable class of multiproduct monopoly models that involve a generalized form of homothetic preferences. This class includes CES, linear and logit demand. Within the class, profit-maximizing quantities are proportional to efficient quantities. We discuss cost-passthrough, including cases where optimal prices do not depend on other products’costs. We show how the analysis can be extended to Cournot oligopoly. Finally, we discuss optimal monopoly regulation when the firm has private information about its vector of marginal costs, and show that if the probability distribution over costs satisfies an independence property, then optimal regulation leaves relative price decisions to the firm.

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