This thesis investigates the competitive dynamics in the global insurance industry from 1999 to 2008. After reviewing the current state of the academic debate on interfirm rivalry, it derives a research agenda spanning different levels of analysis and phenomena of interest. Specifically, the thesis explores (1) how and why firms continuously adjust their strategic profiles in the presence of an industry's strategic group structure, (2) whether market shocks, namely 9/11 and Hurricane Katrina, temporarily change the decision logic underlying competitive choices, and (3) whether stock markets respond differently to competitive moves that follow a clearly stated strategic rationale.