Badanie stabilności współczynnika beta akcji indeksu WIG20

The aim of the article is to examine beta coefficient of WIG20's shares stability. Beta coefficient provides systematic risk measurement, so it's stability is a key factor for effective portfolio management based on beta coefficient. Research reveals beta coefficients high volatility throughout test period of 2001-2012, in particular under financial crisis conditions. Proposed beta coefficient stability ranking reflects combined results of different stability measures: standard deviation, coefficient of variation and mean absolute deviation. Stability ranking is a simple approach to gain some level of statistical objectivity. However, in general beta coefficients of WIG20's shares are highly volatile, what can affect investment portfolio risk and return management.