Imperfect Insurance Markets

The focus of this thesis is on consumer diversity. Incorporating consumer heterogeneity into economic analysis is well-established in industrial organization literature; this aspect is, however, often neglected in microeconomic insurance models. A first new approach lies in analyzing risk interdependencies. When risks are interdependent, an agent's decision to selfprotect affects the loss probabilities faced by others. Due to these externalities, economic agents invest too little in prevention relative to the socially efficient level by ignoring marginal external costs or benefits conferred on others. We analyze an insurance market with externalities of loss prevention. It is shown in a model with heterogenous agents and imperfect information that a monopolistic insurer can achieve the social optimum by engaging in pre-mium discrimination. An insurance monopoly reduces not only costs of risk selection, but may also play an important social role in loss prevention. This result can be empirically confirmed. We also deal with the impact of intermediation on insurance market transparency and performance. In a differentiated insurance market under imperfect information, uninformed consumers may become informed about product suitability by consulting an intermediary. We analyze current broker compensation systems: commissions and fees. While insurers' equilibrium profits are equivalent under both systems, social welfare under fees is first-best efficient. Both systems may offer the opportunity to increase profits via collusion. Under a commission system, collusion enables insurers to separate consumers into groups purchasing different contracts. Insurers may then extract additional rents from some consumers. This might explain why intermediaries tend to be compensated by insurers in practice. Finally, we study optimal monopoly pricing given imperfect information and heterogenous policyholders.