the value of a standard​ & poor's index is computed by
To calculate the value of the S&P 500 Index, the sum of the adjusted market capitalization of all 500 stocks is divided by a factor, usually referred to as the Divisor. For example, if the total adjusted market cap of the 500 component stocks is US $13 trillion and the Divisor is set at 8.933 billion, then the S&P 500 Index value would be 1,455.28. Although the adjusted market capitalization of the entire index can be accessed from Standard & Poor's website, the Divisor is considered to be proprietary to the firm. However, the Divisor's value is approximately 8.9 billion.