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EN
In this article the authors presents an approach to quantifying currency risk based on the methodology of econophysics. This article continues the authors’ study into the currency risk, this time simplifying it for the purpose of rendering it useful for companies without technical abilities. A method of analysing the dependencies between currencies based on correlations is introduced to facilitate the analysis of currency risk involved in being exposed to one or more foreign currencies. Also a model estimating a risk-free horizon is introduced and tested against price formation models and empirical data from FX markets.
EN
In this study we investigate how bankruptcy affects the market behaviour of prices of stocks on Warsaw’s Stock Exchange. As the behaviour of prices can be seen in a myriad of ways, we investigate a particular aspect of this behaviour, namely the predictability of these price formation processes. We approximate their predictability as the structural complexity of logarithmic returns. This method of analysing predictability of price formation processes using information theory follows closely the mathematical definition of predictability, and is equal to the degree to which redundancy is present in the time series describing stock returns. We use Shannon’s entropy rate (approximating Kolmogorov-Sinai entropy) to measure this redundancy, and estimate it using the Lempel-Ziv algorithm, computing it with a running window approach over the entire price history of 50 companies listed on the Warsaw market which have gone bankrupt in the last few years. This enables us not only to compare the differences between predictability of price formation processes before and after their filing for bankruptcy, but also to compare the changes in predictability over time, as well as divided into different categories of companies and bankruptcies. There exists a large body of research analysing the efficiency of the whole market and the predictability of price changes enlarge, but only a few detailed studies analysing the influence of external stimulion the efficiency of price formation processes. This study fills this gap in the knowledge of financial markets, and their response to extreme external events.
PL
W artykule prezentujemy metodę badania efektywności rynku gieł- dowego za pomocą teorii informacji. Efektywność rynku badana jest przez stopień redundancji w szeregach czasowych opisujących zmia- ny cen, a konkretnym narzędziem jest stopa entropii Shannona, którą można także interpretować jako miarę przewidywalności zmian cen (w sensie granicy przewidywalności). Metody tej używamy do anali- zy szeregów czasowych opisujących logarytmiczne zmiany cen akcji wybranych spółek z Giełdy Papierów Wartościowych, które podległy procesowi upadłościowemu. Znane są badania efektywności całego rynku, natomiast nie jest zbadane dogłębnie, jak skrajnie negatywna sytuacja ekonomiczna samej spółki, a konkretnie informacja o niej, wpływa na efektywność procesów cenotwórczych dotyczących jej akcji oraz na przewidywalność zmian cen tych akcji. Przegląd pre- zentowany w niniejszym badaniu, oparty na 44 spółkach giełdowych, jest wstępem do szerszej gamy badań dotyczących wpływu zdarzeń pozagiełdowych na złożoność strukturalną procesów cenotwórczych.
EN
In this study we present a method of analysing market efficiency using information theory. The efficiency of a given market is studied by the degree to which redundancy is present in the time series describing stock returns, while the particular tool used is called Shannon’s en- tropy rate, and can be interpreted as a measure of the predictability of stock returns (understood as the limits of prediction). We use this me- thod to analyse time series describing logarithmic returns of chosen companies listed at Warsaw Stock Exchange, which have undergone bankruptcy. There exists a body of research analysing the efficiency of the whole market, but there are no detailed studies analysing how strongly negative economic situation of a company (and particularly information about this situation) affects the efficiency of price forma- tion processes with regards to the shares of this company, and how it affects the predictability of the changes in the prices of these shares. The review presented in this study, based on 44 stocks, is meant to be a prelude to many detailed studies of the influence of effects of events outside of the stock market on the structural complexity of the price formation processes themselves.
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