In this article, we derive conditions in an imperfect market setting, under which the introduction of a self-supporting insurance guaranty fund improves the position of the policyholders. When a guaranty fund is advantageous given homogeneous firms in the market, all policyholders benefit from it to the same extent, if they have the same underlying risk preferences and are charged identical premiums. In a more realistic heterogeneous setting, the introduction of an insurance guaranty fund is in general no longer beneficial for all policyholders in the same manner. Hence, systematic wealth transfers take place between the policyholders of different insurance companies. As a possible solution, and in order to counteract this effect, we introduce a framework for utility-based fund charges.