Catastrophe bonds (cat bonds) often use index triggers, such as, for instance, parametric descriptions of a catastrophe. This implies the problem of the so-called basis risk, resulting from the fact that, in contrast to traditional reinsurance, this kind of coverage cannot be a perfect hedge for the primary's insured portfolio. On the other hand, cat bonds offer some very attractive economic features: Besides their usefulness as a solution to the problems of moral hazard and default risk, an important advantage of cat bonds can be seen in presumably lower risk premiums compared to (re)insurance products. Cat bonds are only weakly correlated with market risk, implying that in perfect financial markets these securities could be traded at a price including just small risk premiums. Furthermore, there is empirical evidence that risk aversion of reinsurers is an important reason for high reinsurance prices. In this paper we introduce a simple model that enables us to analyze cat bonds and reinsurance as substitutional risk management tools in a standard insurance demand theory environment. We concentrate on the problem of basis risk versus reinsurers' risk aversion and show that the availability of cat bonds affects the structure of an optimal reinsurance contract as well as the reinsurance budget. Primarily, reinsurance is substituted by index-linked coverage for large losses.
