Calculated by the Bulgarian Stock Exchange (BSE), Sofix tracks the performance of the 20 most liquid stocks on the bourse.
Launched in October 2000, with an starting value of 100, it is the oldest index of the Bulgarian stock market and is largely seen as the benchmark of the BSE's performance.
It is periodically expanded to include new stocks that meet a number of requirements, among them certain thresholds concerning market capitalisation, number of shareholders, free float and number of transactions.
Sofix is calculated based on the changes to the number of shares traded, the last price on the day, the free flot on the day and the weight the stock has in the index. Currently, all stocks are equally weighted.