The S&P 500 Index is a modified capitalization weighted index. A pure capitalization index is constructed by first multiplying each stock's price by its total number of shares, second adding these cross-products, and third dividing the sum by the index divisor. Originally, the S&P 500 Index was a pure capitalization index. A modified capitalization index is based on something other than the total, actual number of shares outstanding. On September 16, 2005, S&P changed to a modified capitalization index based on each stock's floating number of shares. Specifically, shares held by any company's control groups in excess of a ten percent threshold will be excluded from the index. Accordingly, the table below reflects floating market capitalizations based on each stock's number of floating shares.