In this paper, the copula theory is used to describe the dependence structure between variables, while the information theory provides the tools necessary to measure the uncertainty associated with these variables. What both theories have in common is copula entropy, which is strictly related to mutual information.
The findings of this study, focusing on the dependence of the (sub)indexes of the Polish stock market during the pandemic period, may prove useful not only to investors from Poland, but also from other countries, especially Central European, in making investment decisions.
The results of calculating the interdependencies between WIG, sectoral indexes and among sectoral indexes of the Polish economy using copula entropy and Pearson’s correlation are quite different.
The source of the basic difference between copula entropy and Pearson’s correlation is that the former enables the measurement of nonlinear interdependencies, while the latter not. The interrelations on the stock markets are nonlinear and returns are not normally distributed in general. The use of copulas is also superior in terms of ranking correlation, as it is more general and allows the examination of the structure of dependencies between extreme values.
Polish subindexes, COVID-19 pandemic, mutual information, copula entropy.
G15, G19
Akhtaruzzaman, M., Boubaker, S., Sensoy, A., (2020). Financial contagion during COVID–19 crisis. Finance Research Letters, vol. 38, Article ID 101604.
Albulescu, C. T., (2020). COVID-19 and the United States financial markets’ volatility. Finance Research Letters, vol. 38, Article ID 101699.
Alomari, M., Power, D. M., Tantisantiwong, N., (2018). Determinants of equity return correlations: a case study of the Amman Stock Exchange. Review of Quantitative Finance and Accounting, 50(1), pp. 33–66.
Ashraf, B. N., (2020). Stock markets’ reaction to COVID-19: cases or fatalities? Research in International Business and Finance, vol. 54, Article ID 101249.
Aslam, F., Awan, T. M., Syed, J. H., Kashif, A., Parveen, M., (2020a). Sentiments and emotions evoked by news headlines of coronavirus disease (COVID-19) outbreak. Humanities and Social Sciences Communications, vol. 7, p. 23.
Aslam, F., Mohti, W., Ferreira, P., (2020b). Evidence of intraday multifractality in European stock markets during the recent coronavirus (COVID-19) outbreak. International Journal of Financial Studies, 8(2), p. 31.
Aslam, F., Aziz, S., Nguyen, D. K., Mughal, K. S., Khan, M., (2020c). On the efficiency of foreign exchange markets in times of the COVID-19 pandemic. Technological Forecasting and Social Change, vol. 161, Article ID 120261
Baig, S., Butt, H, A., Haroon, O., Rizvi S., (2020). Deaths, panic, lockdowns and US equity markets: the case of COVID-19 pandemic. Finance Research Letters, vol. 38, Article ID 101701.
Bakas, D., Triantafyllou, A., (2020). Commodity price volatility and the economic uncertainty of pandemics. Economics Letters, vol. 193, Article ID 109283.
Barberis, N., Shleifer, A., Wurgler, J., (2005). Comovement. Journal of Financial Economics, 75 (2), pp. 283–317.
Chiang, T C., Zheng, D., (2010). An empirical analysis of herd behavior in global stock markets. Journal of Banking & Finance, 34(8), pp. 1911–1921.
Cerqueti, R., Rotundo, G., Ausloos, M., (2018). Investigating the Configurations in Cross-Shareholding: A Joint Copula-Entropy Approach. Entropy, 20(2), pp.134– 134. https://doi.org/10.3390/e20020134.
Fiedor, P., (2014). Networks in financial markets based on the mutual information rate. Physical Review E, 89(5), Article ID 052801.
Fiedor, P., (2015). Mutual information-based hierarchies on Warsaw Stock Exchange. Acta Physica Polonica A, 127(3a), A–33.
Goldestein, I., Pauzner, A., (2004). Contagion of self-fulfilling financial crises due to diversification of investment portfolios. Journal of Economic Theory, 119(1), pp 151–183.
Goodell, W., (2020). COVID-19 and finance: agendas for future research. Finance Research Letters, vol. 35, Article ID 101512.
Huang, Ji C., Cao, Y., Hu, S., (2019). The network structure of Chinese finance market through the method of complex network and random matrix theory. Concurrency and Computation: Practice and Experience, 31(9), Article ID e4877.
Jenison, R., L., Reale, R. A., (2004). The Shape of Neural Dependence. Neural Computation, 16, pp. 665–672.
Joe, H., (1989). Relative entropy measures of multivariate dependence. Journal of the American Statistical Association, 84(405), pp. 157–164.
Khan, S., Bandyopadhyay, S.,. Ganguly, A. R., et al., (2007). Relative performance of mutual information estimation methods for quantifying the dependence among short and noisy data. Physical Review E, 76(2), Article ID 026209.
Kodres, E., Pritsker, M., (2002). A rational expectations model of financial contagion. The Journal of Finance, 57(2), pp. 769–799.
Kwon, O., Yang, J-S., (2008). Information flow between composite stock index and individual stocks. Physica A: Statistical Mechanics and Its Applications, 387(12), pp. 2851–2856.
Leduc, S., Liu, Z., (2020). The uncertainty channel of the coronavirus. FRBSF Economic Letter, 7, pp. 1–5.
Long, W., Guan, L., Shen, J., Song, L., Cui, L., (2017a). A complex network for studying the transmission mechanisms in stock market. Physica A: Statistical Mechanics and Its Applications, 484, pp. 345–357.
Long, W., Tang, Y., Cao, D., (2016). Correlation analysis of industry sectors in China’s stock markets based on interval data. Filomat, 30(15), pp. 3999–4013.
Long, H., Zhang, J., Tang, N., (2017b). Does network topology influence systemic risk contribution? a perspective from the industry indices in Chinese stock market. PLoS One, 12(7), Article ID e0180382.
Mazur, M. D., Vega, M., (2020). COVID-19 and the March 2020 stock market crash. evidence from S&P1500. Finance Research Letters, vol. 38, Article ID 101690.
Ma, J., Sun, Z., (2011). Mutual Information Is Copula Entropy. Tsinghua Science & Technology, 16(1), pp. 51–54.
Nelsen, R. B., (2006). An Introduction to Copulas. 2nd Edition, Springer, New York. Okorie, D. I., Lin B. Q., (2020). Stock markets and the COVID-19 fractal contagion effects. Finance Research Letters, vol. 38, Article ID 101640.
Qiao, H., Xia, Y., Li Y., (2016). Can network linkage effects determine return? evidence from Chinese stock market. PLoS One, 11(6), Article ID e0156784.
Poynter, J. G., Winder, J. P., Tai, T., (2015). An analysis of comovements in industrial sector indices over the last 30 years. Review of Quantitative Finance and Accounting, 44(1), pp. 69–88.
Rizwan, S., Ahmad, G., Ashraf, D., (2020) Systemic risk: the impact of COVID-19. Finance Research Letters, vol. 36, Article ID 101682.
Scharfstein, D. S., Stein J. C., (1990). Herd behavior and investment. American Economic Review, 80(3), pp. 465–479.
Sharif, A., Aloui, C., Yarovaya, L., (2020). COVID-19 pandemic, oil prices, stock market, geopolitical risk and policy uncertainty nexus in the US economy: fresh evidence from the wavelet-based approach. International Review of Financial Analysis, vol. 70, Article ID 101496.
Shehzad, K., Xiaoxing, L., Kazouz, H., (2020). COVID-19’s disasters are perilous than global financial crisis: a rumor or fact? Finance Research Letters, vol. 36, Article ID 101669.
Sklar, A., (1959). Functions de Repartition an Dimension Set Leursmarges. Publications de L’In-stitut de Statistique de L’Universite de Paris.
Sukcharoen, K., Leatham, D. J., (2016). Dependence and extreme correlation among US industry sectors. Studies in Economics and Finance, 33(1), pp. 26–49.
Surya, C., Natasha, G., Natasha, G., (2018). Is there any sectoral cointegration in Indonesia equity market? International Research Journal of Business Studies, 10(3) pp. 159–172.
Tenzer, Y., Elidan, G., (2016). On the Monotonicity of Copula Entropy. arXiv:1611.06714v1 [math.ST].
Yang, C., Chen, Y., Hao, W., Shen, Y., Tang, M., Niu L., (2014). Effects of financial crisis on the industry sector of Chinese stock market-from a perspective of complex network. Modern Physics Letters B, 28(13), Article ID 1450102.
Yang, C., Shen, Y., Xia, B., (2013). Evolution of Shanghai stock market based on maximal spanning trees. Modern Physics Letters B, 27(03), Article ID 1350022.
Wang, Y., Yue, J., Liu, S., Wang, L., (2017). Copula Entropy coupled with Wavelet Neural Network Model for Hydrological Prediction. IOP Conf. Series: Earth and
Environmental Science, 113(2018), 012160, doi :10.1088/1755-1315/113/1/012160
Wang, X. D., Hui, X. F., (2018). Cross-sectoral information transfer in the Chinese stock market around its crash in 2015. Entropy, 20(9), pp. 1–14.
Zaremba, A., Kizys, R., Aharon, D. Y., Demir, E., (2020). Infected markets: novel coronavirus, government interventions, and stock return volatility around the Globe. Finance Research Letters, vol. 35, Article ID 101597.
Zhang, D, Hu, M., Ji, Q., (2020). Financial markets under the global pandemic of COVID-19. Finance Research Letters, vol. 36, Article ID 101528.
Zhao, N., Lin, W., (2011). A copula entropy approach to correlation measurement at the country level. Appl. Math. Comput, 218(2), pp. 628–642.