Similar to Mayers and Smith (1990), Choi and Weiss (2005), Cole and McCullough (2006) and Leverty and Grace (2010), I have measured the concentration of the lines of business and the states they operate in, using the Herfindahl index to express both states and lines of business. The Herfindahl index has been used to characterize the market of each insurance company in terms of geography and business type. The state Herfindahl index for each company can be written as,