Sector strength and efficiency on developed and emerging financial markets

In this paper we analyse the importance of sectors and market efficiency on developed and emerging financial markets. To perform this we analyse New York Stock Exchange between 2004 and 2013 and Warsaw Stock Exchange between 2000 and 2013. To find out the importance of sectors we construct minimal spanning trees for annual time series consisting of daily log returns and calculate centrality measures for all stocks, which we then aggregate by sectors. Such analysis is of interest to analysts for whom the knowledge of the influence of particular groups of stocks to the market behaviour is crucial. We also analyse the predictability of price changes on those two markets formally, using the information-theoretic concept of entropy rate, to find out the differences in market efficiency between a developed and an emerging market, and between sectors themselves. We postulate that such analysis is important to the study of financial markets as it can contribute to the profitability of investments, particularly in the case of algorithmic trading.