The base dates used are 16 August 16, 1995 (SET50 Index) and 30 April 2005 (SET100 Index), which are the respective dates that the two indices were first published and were set to a base value of 1000 points.
The list of component stocks in the SET50 Index and the SET100 Index are revised every six months in order to adjust for any unexpected changes that have occurred in the stock market such as new listings or public offerings.
Stock selection is conducted semi-annually between December 1–31 and June 1–30.
New SET100 and SET50 Indices will take effect on the first trading day in January and July of each year.
Also, adjustments will be made whenever the market value of a component stock changes due to the conversion of convertible bonds, the exercising of warrants, or new shares are issued for capital increase of the component stock, etc.