Percorrer por autor "Dias, Rui"
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- Do investors tend to overreact when investing in clean energy stock indices?Publication . Dias, Rui; Galvão, Rosa; Cruz, Sandra P.; Gonçalves, Sidalina; Irfan, Mohammad; Teixeira, Nuno; Alexandre, Paulo; Palma, Cristina; Almeida, LilianaDue to climate change, investors are increasingly interested in clean energy stocks attracting many investors due to clean energy prospects. This paper analyses investor overreactions to long-term prices in various clean energy stock indices, such as Clean Energy Fuels (CLNE), Global Clean Energy (GCEI), as well as the Dow Jones Industrials (DJI) stock index, over the period from 24 February 2022 to 23 May 2024. The results show that the Global Clean Energy (GCEI) clean energy stock index rejects H0 at the 16-day lag at a significance level of 1%; similarly, the Clean Energy Fuels (CLNE) index rejects the null hypothesis at lags 8, 9, 10, 11 and 12 days, both indices show negative serial autocorrelation, which means that price movements are not entirely random and are influenced by prior price movements. This evidence could mean that investors overreact to the information that reaches the market. On the other hand, the ETF (PWYF) and the Dow Jones Industrial Stock Index (DJI) show that the random walk hypothesis has not been rejected. In other words, these markets show that they are in equilibrium and that the existence of exaggerated reactions on the part of investors is not significant. The answer to the research question was partially accepted, so the Russian invasion of Ukraine in 2022 led to the partial presence of overreactions in these stock indices. In conclusion, investors operating in these markets should exercise caution and consider their risk tolerance before investing. Investors should, therefore, continue to monitor market trends and adjust their investment strategies accordingly.
- Estratigrafia II – Quadros das divisões estratigráficasPublication . Cardoso, João Luis; Dias, Rui; Sousa, M. J. Lemos de; Moreira, Patrícia; Rodrigues, Cristina F. A.; Salgado, Ana; Sousa, M. J. Lemos de; Antunes, M. Telles; Salgado, AnaDois anos volvidos, um novo volume do Thesaurus vê agora a luz do dia — trata da Estratigrafia, mais concretamente dos Quadros das Divisões Estratigráficas.
- Exploring the relationship between clean energy indices and oil prices: a ten-day window approachPublication . Dias, Rui; Galvão, Rosa; Cruz, Sandra P.; Irfan, Mohammad; Teixeira, Nuno; Gonçalves, SidalinaThis paper aims to assess the comovements between clean energy indices, namely the Clean Energy Fuels (CLNE), Nasdaq Clean Edge Green Energy (CELS), S&P Global Clean Energy (SPGTCLEN), TISDALE Clean Energy (TCEC.CN), Wilderhill (ECO), West Texas Intermediate (WTI) stock indices, over the period from 1 January 2018 to 23 November 2023. We used 10-day windows to analyse the duration and nature of the shocks. Granger causality tests revealed that 20 of the 30 possible pairs showed significant movements, with the WTI influencing all the clean energy indices, highlighting its global importance. CELS also showed a robust influence on all pairs, while SPGTCLEN had a significant but less far-reaching influence. The CLNE and ECO indices showed limited influences, suggesting the potential for diversification, the TCEC.CN proved to be independent and a determining factor for portfolio diversification. The Impulse Response Functions (IRF) confirmed significant movements between CELS, SPGTCLEN and WTI, reflecting the market's response to policies and adjustments in expectations. Fluctuations in oil prices substantially affect clean energy indices, highlighting the interconnectedness and volatility of these markets. In conclusion, these results indicate that despite the growth of clean energy, the sector is still influenced by fluctuations in the fossil fuel market.
- Integrated reporting: a literature reviewPublication . Cruz, Sandra P.; Dias, Rui; Varela, Miguel; Galvão, RosaBackground: Integrated Reporting (IR) is an innovative and effective reporting model combining financial and non-financial information into a single report. Purpose: This paper reviews the literature concerning Integrated Reporting related to voluntary disclosure. The study analyses the theoretical foundations of Integrated reporting. It discusses the main dimensions of the concept from the perspective of the company and other stakeholders, highlighting the importance of Integrated Reporting and integrated thinking in how the companies communicate. It aims to summon these points of view and achieve, through a systematic literature review, a clear depiction of voluntary disclosure using Integrated Reporting. Methods: A systematic literature review was performed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology. Prisma is a framework of evidence-based elements designed to help authors conduct systematic literature reviews. Results: The results confirm the benefits a company can have when adopting quality integrated reporting. It promotes a long-term vision of corporate management, improves the diffusion of a culture of sustainability within the company, and promotes integrated thinking, an innovative strategic and cultural approach to corporate management. The limitations involved in adopting integrated reporting were also highlighted. Conclusion: This systematic literature review sought to consolidate knowledge on the subject. Opportunities for further empirical research in this area are suggested.
- The Portuguese (PT) version of the “International Chronostratigraphic Chart”: a new approachPublication . Cardoso, João Luis; Dias, Rui; Sousa, M. J. Lemos de; Moreira, Patrícia; Rodrigues, Cristina F. A.; Salgado, AnaThe Academy of Sciences of Lisbon conducted an extensive study to establish an updated Portuguese (PT) terminology for chronostratigraphic/geochronologic units of selected Geological Timetables.
- Quadros das divisões estratigráficasPublication . Cardoso, João Luis; Dias, Rui; Sousa, M. J. Lemos de; Moreira, Patrícia; Rodrigues, Cristina F. A.; Salgado, Ana; Sousa, M. J. Lemos de; Salgado, Ana
- Quadros das divisões estratigráficas internacionais. IUGS, versão 2023/04Publication . Cardoso, João Luis; Dias, Rui; Sousa, M. J. Lemos de; Moreira, Patrícia; Rodrigues, Cristina F. A.; Salgado, Ana; Sousa, M. J. Lemos de; Salgado, Ana
- Quadros das divisões estratigráficas. Vade-MécumPublication . Cardoso, João Luis; Dias, Rui; Sousa, M. J. Lemos de; Moreira, Patrícia; Rodrigues, Cristina F. A.; Salgado, Ana; Sousa, M. J. Lemos de; Antunes, M. Telles; Salgado, AnaO presente trabalho é um resumo, para facilitar a utilização prática da temática tratada na obra mais desenvolvida dada à estampa sob o título Quadro das Divisões Estratigráficas, integrada na série Thesaurus de Ciências da Terra e editada pela Academia de Ciências de Lisboa (Cardoso et al. 2023). Este vade-mécum corresponde, outrossim, a um parecer consolidado sobre o mesmo assunto, elaborado conjuntamente pela 4.ª seção (Ciências da Terra e do Espaço) da Classe de Ciências e do Instituto de Lexicologia e Lexicografia da Língua Portuguesa, ambos da Academia. Neste enquadramento, do presente trabalho apenas constam, para além da enumeração de regras básicas e tópicos históricos, a terminologia fixada pela Academia das Ciências de Lisboa para figurar nos quadros abaixo listados, completada, sempre que julgado pertinente, por notas explicativas, justificando as principais opções tomadas. Referimo-nos aos quadros abaixo enumerados, que, obviamente, apresentam unidades cronostratigráficas/geocronológicas: – Quadro das Divisões Estratigráficas Internacionais; – Quadro das Divisões Estratigráficas do Ordovícico Ibero-Boémico e sua correlação com os sistemas internacional e do Reino Unido; – Quadro das Divisões Estratigráficas do Carbonífero da Europa Ocidental e a sua correlação com o sistema internacional; – Quadro das Divisões Estratigráficas e da Cronologia do Quaternário.
- Testing the diversifying asset hypothesis between clean energy stock indices and oil pricePublication . Dias, Rui; Galvão, Rosa; Cruz, Sandra P.; Irfan, Mohammad; Alexandre, Paulo; Gonçalves, Sidalina; Teixeira, Nuno; Palma, Cristina; Almeida, LilianaIn theory, geopolitical risk and political uncertainty can directly affect energy markets. Fluctuations lead to the cost of clean energy sources as they compete with traditional energy. The purpose of this study is to analyse financial integration and test the diversifying asset hypothesis between clean energy indices, specifically the Clean Energy Fuels (CLNE), Nasdaq Clean Edge Green Energy (CELS), S&P Global Clean Energy (SPGTCLEN), TISDALE Clean Energy (TCEC.CN), Wilderhill (ECO) and West Texas Intermediate (WTI) stock indices, over the period from 1 January 2018 to 23 November 2023. Analysing the results reveals a scenario where most of the clean energy indices show cointegration with each other, indicating long-term relationships that reflect common trends in the clean energy sector. However, the relative independence of the WTI suggests that Oil still acts as an important and potentially diversifying external factor for investors focused on sustainable energy. Structural breaks in 2021 and 2022 in several indices point to significant events that have altered market dynamics, possibly including changes in environmental policies, technological innovations and the impacts of the COVID-19 pandemic. The cointegration evidence and structural breaks provide valuable information for building investment portfolios. Investors can consider the WTI to diversify portfolios dominated by clean energy assets, taking advantage of Oil’s relative independence. On the other hand, the high correlation between clean energy indices suggests that, within this sector, diversification options are more limited, requiring careful analysis of the specific characteristics of each index and the macroeconomic forces affecting them.