The aim of this study is to determine whether (and to what extent) the weak form of efficient-market hypothesis could be considered true in relation to the financial instruments listed on the Warsaw Stock Exchange in relation to the exchanges of Baltic Sea countries. With respect to the analyzed indices three types of randomness tests were performed: autocorrelation test, series test and unit root test. The direct practical implication of this paper is the assumption that the selected active investment strategies can be successfully used for some groups of shares quoted on WSE, as well as for selected European exchanges.

The aim of this paper is to analyze the occurrence of the so called day of the week effects in market return time series from the period of January 2003 to September 2013 (and additionally January 1999 to December 2002). The study focuses on four indices of the Warsaw Stock Exchange (WIG, WIG20, mWIG40 and sWIG80) and additionally five indices of major world stock exchanges (NIKKEI 225, DAX, CAC40, S&P 500, and IBEX). The main data sample was divided into three subperiods in order to determine whether or not the intensity of day of the week anomalies is constant in time. The study revealed a substantial number of the day of the week anomalies in earliest subperiods and very limited evidence of those effects in later ones, giving rise to the conclusion that the intensity of the day of the week anomalies is diminishing with time. The most common effect identified on the WSE was a positive Friday effect. The Monday effect often described in early literature on the subject matter seems to currently occur very rarely. The study also indicates that the day of the week effects were more persistent among stocks with smaller market capitalization on the WSE.

Purpose – The aim of the paper is the evaluation of the results of Polish socially responsible funds during the pandemic period in comparison to two previous subperiods. Research method – In the research, the nonclassical meters of investment efficiency were used. They were designed for three research subperiods. They provided the basis for creating rankings and for studying the stability of results. The results were compared with the WIG and WIG-ESG index results.Results – The studied socially responsible funds noted lower results in the period directly before the pandemic. In the pandemic period, they, however, noted higher results than the WIG index.Originality / value / implications / recommendations – The paper bridges the research gap pertaining to the research on the results of Polish socially responsible funds during the pandemic period. The article, according to the authors’ knowledge, is one of the first papers in Poland which studies the results of socially responsible funds during the pandemic period.