Liudmyla Sliusareva

This paper explores price effects in the “passion investments” market after days with abnormal returns. To do this, daily prices for stamps and diamonds over the periods 1999–2021 and 1989–2021 are analyzed. The following hypothesis is tested: One-day abnormal returns create stable patterns in price behavior on the next day. Statistic tests (t-test, ANOVA, Mann–Whitney U test, modified cumulative abnormal returns approach, regression analysis with dummy variables) confirm the presence of price patterns related to extreme returns: price fluctuations on the day after extreme returns are higher than returns on “normal” days. On the days after positive abnormal returns, the momentum effect is detected. Contrarian effect is typical for the days after negative abnormal returns. A trading strategy based on detected price effects showed the presence of exploitable profit opportunities. Results of this paper provide additional pieces of evidence in favor of inconsistencies between the efficient market hypothesis and practice and can be used by traders to generate extra profits in the “passion investments” market.

Acknowledgment
The authors gratefully acknowledge financial support from the Ministry of Education and Science of Ukraine (0121U100473).

This paper examines momentum and contrarian effects in the Ukrainian stock market after one-day abnormal returns. To do this, UX futures data over the period 2010–2018 are used. The following hypotheses are tested: H1) hourly returns on overreaction days differ from hourly returns on normal days, H2) there are price patterns on overreaction days, and H3) to test these hypotheses, visual inspection and average analysis are used, as well as t-tests, cumulative abnormal returns, and trading simulation approaches. The results suggest that there are statistically significant differences between intraday dynamics during the usual days and the overreactions day. There is a strong momentum effect present on the day of overreaction: prices tend to change only in the direction of the overreaction during the whole day. The fact of the overreaction becomes clear after 13:00-14:00. This gives a lot of time to explore the momentum effect in the day of overreaction. On the day after the overreaction, prices tend to go in the opposite direction: contrarian pattern is detected, which is in line with the overreaction hypothesis. Based on detected price patterns, rules of trading and trading strategies for the Ukrainian stock market are developed. Momentum Strategy (based on price patterns on the day of overreaction) generates several successful trades; close to with 90%, and their number being is profitable (trading results differ from the random ones – confirmed by t-tests). Contrarian Strategy (based on price patterns on the day after the overreaction) demonstrates low efficiency, and results do not differ from random trading.

Type of the article: Research Article

This paper explores how Russia uses the international academic sphere, including scientific papers, scientometric databases, international publishers, and international organizations, as a propaganda tool to legitimize its appropriation of Ukrainian territories and Ukrainian academic institutions there. To do this, a bibliometric analysis was used. The results showed that thousands of academic papers published in 2014–2024 in peer-reviewed journals by Russian academicians marked Ukrainian territories as those referring and affiliated with the Russian Federation. The same is true for the case of editorial boards of international journals, where Ukrainian cities were incorrectly marked as part of the Russian Federation. Quite often, those organizations that provide affiliations in the occupied territories of Ukraine are not even legitimate: they were created by Russia using the captured Ukrainian scientific infrastructure and often named similarly or the same as the existing Ukrainian institutions-in-exile. It is important that the international scientific community put an end to this misuse of its resources. The study findings highlighted the importance and urgency of coordinated actions from academic journals, publishing platforms, and scientometric databases towards vigilant oversight of the content they host and accountability of the authors to prevent the dissemination, indexing, or promotion of Russian narratives and propaganda related to the appropriation of the Ukrainian territories.

Acknowledgment
Alex Plastun gratefully acknowledges financial support provided by Volkswagen Foundation, Ref.: 9C853, Project “Sustaining Ukrainian Scholarship”, hosted by New Europe College.