Investment horizon approach has been used to analyze indexes of Polish stock market. Optimal time horizon for each return value is evaluated by fitting appropriate function form of the distribution. Strong asymmetry of gain--loss curves is observed for WIG index, whereas gain and loss curves look similar for WIG20 and for most stocks of individual companies. The gain--loss asymmetry for these data, measured by a coefficient, that we postulated before [submitted to {ITALIC Physica A}], has opposite sign to this for WIG index.

PACS numbers: 89.65.Gh, 02.50.--r, 89.90.+n