Type of Document	Dissertation
Author	Wang, Yuling
URN	etd-07072009-214151
Title	Two Essays On Property-Liability Insurer Rating Transitions
Degree	Doctor of Philosophy
Department	Risk and Insurance, Department of
Advisory Committee	Advisor Name Title James M. Carson Committee Chair Cassandra Cole Committee Member Kathleen A. McCullough Committee Member Patrick F. Maroney Committee Member Randy E. Dumm Committee Member Richard B. Corbett Committee Member Pamela K. Coats Outside Committee Member
Keywords	Insurer Rating Drift Macroeconomic and Market Predictors Insurer Rating Transitions
Date of Defense	2009-06-04
Availability	unrestricted
Abstract My dissertation examines property-liability insurer rating transitions for the period 1995 through 2006. The sample includes over 2,000 US insurers and 10 years of ratings data from A.M. Best. Rating transitions reflect changes in insurer “default risk”, and this area has not been fully explored in the insurance literature. This dissertation studies the predictors of insurer rating transitions and the non-Markovian behaviors within insurer rating movements. The research questions and results are presented in two essays. The first essay, Macroeconomic Factors and Property-Liability Insurer Rating Transitions, identifies the exogenous macroeconomic and market factors that predict rating transitions, while controlling for certain firm-specific characteristics such as rating history, firm size, business mix, and organization types. Realizing the possible multiple spells (multiple upgrade or downgrade transitions for an insurer during the sample period), I apply the PWP-Gap model, a powerful survival analytical technique. The results suggest that the intensities of insurer rating transitions, including upgrade and downgrade transitions, are linked to macroeconomic and market covariates. Macroeconomic factors are more influential in the upgrade intensity, while market factors are more influential in the downgrade intensity. The second essay, The Importance of Rating Drift Among Property-Liability Insurers, detects rating drift phenomena, which have been explored in the bond literature, but not yet in insurer rating transitions. With a survival analytical technique—Cox Proportional Hazard Model--three main rating drift phenomena are examined: first-rating phenomenon, momentum drift phenomenon, and time dependence phenomenon. I find that those rating drift phenomena observed in the bond rating movements are present for insurer rating migrations. The findings of the current study carry implications for various parties in the insurance market. For regulators, this study suggests that information about rating changes can be used as potential early indicators of insurer financial strength. For consumers and agents, this study suggests consumers and agents should be especially observant of insurer rating downgrades, especially when in turbulent economic environments and severe industry conditions. For insurers, this study suggests insurers may use the results here to manage their own operation risk, taking into account the various exogenous and endogenous environments. In addition, for the investors in insurance companies, the results may be useful in developing various investment strategies.
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