Using a sample of property-liability insurers over the period 1995-2004, we develop and test a model that explains performance as a function of line-of-business diversification and other correlates. Our results indicate that undiversified insurers consistently outperform diversified insurers. In terms of accounting performance, we find a diversification penalty of at least 1 percent of return on assets or 2 percent of return on equity. These findings are robust to corrections for potential endogeneity bias, alternative risk measures, alternative diversification measures, and an alternative estimation technique. Using a market-based performance measure (Tobin's Q) we find that the market applies a significant discount to diversified insurers. The existence of a diversification penalty (and diversification discount) provides strong support for the strategic focus hypothesis. We also find that insurance groups underperform unaffiliated insurers and that stock insurers outperform mutuals. Copyright (c) The Journal of Risk and Insurance, 2008.

No abstract

No abstract

Regulators, investors, consumers, and insurance brokers use insurer financial strength ratings to evaluate the insolvency risk of insurers. This article investigates the factors influencing the decision to obtain a rating or multiple ratings, the determinants of ratings for the three major insurer rating agencies, and reasons for differences in ratings across agencies. This study indicates that insurers obtain ratings to reduce ex ante uncertainty about insolvency risk. It also provides evidence that specific rating determinants and their weights differ across agencies. Evidence of sample selection bias is found only in relation to Best's ratings.

Internal capital markets, insurance, reinsurance, G22, G32,