The enactment of property–casualty insurance guaranty fund statutes in the US was associated with a decrease in insurers' reserves for Homeowners and Commercial Multi-Peril insurance. The evidence is: loss ratios among states enacting guaranty fund statutes declined relative to other states. Tests on loss accruals confirm that the effect was due to decrease in reserves. Other tests that distinguish between guaranty fund statutes offer no evidence that guaranty funds encouraged sound insurers to monitor competitors and assist regulators in identifying weak insurers. Instead, the data are consistent with an explanation where insurance regulators identify and discourage risk-increasing activity.