G14 - Information and Market Efficiency; Event Studies; Insider TradingReturn

In efficient markets, asset prices perform a random walk. Excessive returns cannot be repeatedly and systematically achieved in such markets. To test the weak form of market efficiency, statistical tests are used to identify dependencies in the movements of asset prices. This paper deals with testing of the weak form of market efficiency using daily data of the development of stock indices on the Czech, Polish, German and Dutch markets in the period 2001-2022. The article uses the runs test, the autocorrelation analysis, two variants of the unit root test and the variance ratio test. The results of the tests performed are mixed. The weakly efficient behavior of the investigated markets was pointed out only by the runs tests and partly by the autocorrelation analysis. According to the runs test, only the Dutch market behaved weakly efficiently in all monitored periods, while the Czech, Polish and German markets behaved weakly efficiently in four of the five monitored periods. Autocorrelation analysis indicated the occurrence of the random walk in some periods especially on the Polish market, partly on the Czech market and rarely on the German market.

This paper analyzes the impact of weather on the investment in the Czech and U.S. stock markets. It relies on the concept of behavioral finance, which analyzes the impact of psychology on investor decision-making. The influence of atmospheric phenomena is mainly studied as impact of occurrence of snow, rain or fog on the market returns. The research results show the impact of these phenomena only in a minority of cases. The research also analyzes the impact of the autumn season (SAD effect) on the psychology of investors and therefore market returns. This sequence wasn't rebutted only at the Czech stock market. The incidence of observed atmospheric effects also failed to explain the January and Monday effects.

This assay discusses with an opinion that sees the responsibility of an economic entity in practice only in the instrument of guarantee and in the responsibility of management. This article notices, that the responsibility of entity is realised in practice not until critical situation, but during all entity life. The instrument to it is the mandatory disclosure of information. Its extent is different in various countries. As for corporation, the requirements on disclosure are imbedded in generally accepted OECD Principles of Corporate Governance. Majority of these requirements is supported by both sets of multinational financial reporting standards - IFRS as well as US GAAP. In the demands to the presentation of the internal control systems and entity risk management these standards go beyond OECD claims.