Limited risk of Catastrophically Large Losses

The essential risk is often aggregation. If the same event can cause losses to numerous policyholders of the same insurer, the ability of that insurer to issue policies becomes constrained, not by factors surrounding the individual characteristics of a given policyholder, but by the factors surrounding the sum of all policyholders so exposed. Typically, insurers prefer to limit their exposure to a loss from a single event to some small portion of their capital base, on the order of 5 percent. Where the loss can be aggregated, or an individual policy could produce exceptionally large claims, the capital constraint will restrict an insurer's appetite for additional policyholders. The classic example is earthquake insurance, where the ability of an underwriter to issue a new policy depends on the number and size of the policies that it has already underwritten. Wind insurance in hurricane zones, particularly along coast lines, is another example of this phenomenon. In extreme cases, the aggregation can affect the entire industry, since the combined capital of insurers and reinsures can be small compared to the needs of potential policyholders in areas exposed to aggregation risk. In commercial fire insurance it is possible to find single properties whose total exposed value is well in excess of any individual insurer’s capital constraint. Such properties are generally shared among several insurers, or are insured by a single insurer who syndicates the risk into the reinsurance market.