A security’s eligibility for inclusion is dependent on its trading value on the main board compared to the market average from June 1, 2005 – May 31, 2006. Eligible firms must be among the top 200 securities having the highest daily average market capitalization values for the past 12 months.
Other criteria include being listed for at least six months, and having a free-float of no less than 20%. Stocks which have been delisted or suspended for a lengthy period or are being considered for such action are ineligible.
The SET50 index will be calculated using the top 50 eligible securities, while the top 100 will form the basis of the SET100 index. Should a company lose its eligibility, a replacement will be drawn from the next five securities just beyond the current list of included firms.