The Nikkei JASDAQ Stock Average (Nikkei JASDAQ Average) is a price-weighted stock index adjusted by "Dow adjustment", same as the Nikkei 225. This index was called the Nikkei Over-The-Counter Stock Average when it started the calculation.
The Nikkei JASDAQ Average is comprised of all domestic common stocks in the JASDAQ of the Tokyo Stock Exchange, excluding Bank of Japan, ETFs, REITs, preferred equity contribution securities, tracking stocks (on subsidiary dividend) etc other than common stocks.
The presumed value is set for each constituent, which succeeds “par value system” used to be introduced for Japanese stocks, and the each constituent stock price is adjusted by the presumed par value. The Nikkei JASDAQ Average is calculated by dividing the summation of the adjusted prices by the divisor. The purpose of the divisor is to maintain the continuity of the index by eliminating the effect of external factors not directly related to the market movement in calculating the price-weighted index. This method using the divisor is called “Dow adjustment”.
Base date etc
The commencement date of the calculation was April 1st, 1985 (calculated retroactively back to November 11th, 1983). Since July 16th 2013, the Nikkei JASDAQ Average is currently calculated every 15 seconds while the Tokyo Stock Exchange opens (calculated every 1 minute previously).