The Borsa Istanbul 100 Index also referred to as BIST100 is a capitalization-weighted index composed of 100 companies listed in the Istanbul Stock Exchange with the highest volume and market value, except investment trusts. The constituents of the BIST National 100 Index are selected on the basis of pre-determined criteria directed for the companies to be included in the indices. The base date is January 1986 and base value is 1 for the TL based price.