ISS uses the following four indexes for comparative purposes.
S&P 500 index
S&P MidCap 400 index
S&P SmallCap 600 index
Russell 3000 index excluding the members of the S&P 500, S&P MidCap 400 and S&P SmallCap 600 indexes
Industry Groups
ISS's industry grouping system is based on the Global Industry Classification Standard (GICS) codes developed by Standard & Poor's and Morgan Stanley Capital International.
The following is a list of 23 industry groups classified based on the 4 digit GICS codes.