Update : Nov. 21, 2011
The Tokyo Stock Price Index ('TOPIX') is a composite index of all common stocks listed on the First Section of Tokyo Stock Exchange (TSE).The index is basically a measure of the changes in aggregate market value of TSE common stocks. The base for the index is the aggregate market value of its component stocks as of the close on January 4, 1968. The aggregate market value is calculated by multiplying the number of listed shares of each component stock by its price and totaling the products derived there from.
In computing the index, the base market value is used as the denominator of a fraction whose numerator represents the current aggregate market value. The fraction so obtained is multiplied by 100 (the index value on the base date) and is reduced to a decimal figure to the nearest one-hundredth for each of the indices computed.
In addition to TOPIX, TSE computes and publishes TOPIX subindices for each of the 33 industry groups, 3 indices for large, medium and small sized companies, and the TOPIX New Index Series.