Although the economic motivation and efficiency effects of mergers and acquisitions (M & As) in the insurance industry have been discussed, none of the prior studies have addressed the relationship between M & A activity and insurance price change. In addition, little is known about the effect of diversification on the differences in insurance price across lines. The main objective of the dissertation is to provide evidence on these issues. A secondary objective is to investigate the relationship between M & A activity and insurer’s efficiency and financial performance. We also examine various firm characteristics that affect insurance price differences across lines and that influence insurer’s efficiency and performance. We conduct fixed effects model regressions to test our hypotheses using unbalanced panel data over the sample period 1989-2004. The empirical tests indicate that the price of insurance for newly formed insurers decreases following the M & As and diversified insurers charge lower prices than less diversified firms. Our result is consistent with one possible explanation that acquiring insurers reduce overall underwriting risks and more efficiently manage the frictional costs of capital through geographic and/or product line diversification by engaging in the M & As and therefore gain a competitive advantage in pricing. Our analysis also reveals a number of other interesting results. We find that insurance price is positively related to marginal capital allocation and inversely related to firm insolvency put value, suggesting the importance of incorporating insolvency risk and marginal capital costs in pricing lines of insurance business. We also find that the price of insurance is inversely related to cost efficiency, consistent with the efficiency structure hypothesis. However, the market share variable is not significant, implying that market power that can arise from M & A activity may not be a big concern for insurance regulators. In the analysis of efficiency and financial performance, we provide evidence that acquirers’ overall cost and revenue efficiency and financial performances decrease following M & As. We also find that more focused insurers outperform the diversified insurers.