2. Calculate the total market value of all stocks on that day.
3. The total market value of the day is divided by the total market value of the Shanghai Composite Index in the base period, and then multiplied by100;
For example, the Shanghai Composite Index is based on xx and xx. The total market value of that day was 1 billion, and today it is 20 billion. Because the index of that day was 100, it is now (200/1) *100 = 20000;