Rossella Argenziano

Differentiated Networks: Equilibrium and Efficiency

We consider a model of price competition in a duopoly with product differentiation and network effects. The value of a good for a consumer is the sum of a common and an idiosyncratic component. The first captures the vertical dimension of quality, the second captures horizontal differentiation. Each consumer privately observes his own value for each good, but cannot separate the common and the idiosyncratic component. Therefore, he has incomplete information about the value of the goods for the other consumers. After firms announce prices, consumers choose simultaneously which network to join, facing a coordination problem. In the efficient allocation, both networks are active and the firm with the highest expected quality has the largest market share. To characterize the equilibrium allocation, we derive necessary and sufficient conditions for uniqueness of the equilibrium of the coordination game played by consumers for given prices. The equilibrium allocation differs from the efficient one for two reasons. First, the equilibrium allocation of consumers to the networks is too balanced, since consumers fail to internalize network externalities. Second, if access to the networks is priced by strategic firms, then the product with the highest expected quality is also the most expensive. This further reduces the asymmetry between market shares and therefore social welfare.

Clustering in N-Player Preemption Games

We study a complete information preemption game in continuous time. A finite number of firms decide when to make an irreversible, observable investment. Upon investment, a firm receives flow profits, which decrease in the number of firms that have invested. The cost of investment declines over time exogenously. We characterize the subgame-perfect equilibrium outcome, which is unique up to a permutation of players. When the preemption race among late investors is sufficiently intense, the preemption incentive for earlier investors disappears, and two or more investments occur at the same time. We identify a sufficient condition in terms of model parameters: clustering of investments occurs if the flow profits from consecutive investments are sufficiently close. This shows how clustering can occur in the absence of coordination failures, informational spillovers, or positive payoff externalities.

Inefficient Entry Order in Preemption Games

In a preemption game, players decide when to take an irreversible action. Delaying the action exogenously increases payoffs, but there is an early mover advantage. Riordan (1992) shows that in a preemption game with two asymmetric players, players act in decreasing order of efficiency. This provides a microfoundation to the assumption that entry in a market occurs in the order of profitability, commonly used in the empirical analysis of market entry. We provide a counterexample showing that with more than two players this intuitive result can be reversed. We present a preemption game of entry into a new market. The potential entrants are three asymmetric firms: one “efficient” firm with high post-entry profits, and two “inefficient firms”. We show that the set of parameters such that the equilibrium entry order does not reflect the efficiency ranking is nonempty, and analyse which changes in post-entry profits preserve this entry order.