Mariana Chambino – Polytechnic Institute of Setúbal, (ESCE/IPS), 2910-761 Setúbal, Portugal

Rui Dias – Polytechnic Institute of Setúbal, (ESCE/IPS), 2910-761 Setúbal, Portugal; Center of Advanced Studies in Management and Economics, University of Évora, 7004-516 Évora, Portugal

Cristina Morais da Palma – Polytechnic Institute of Setúbal, (ESCE/IPS), 2910-761 Setúbal, Portugal

Keywords:                    Events for 2020 and 2022;
Clean energy stock index;
Persistence in returns;
Portfolio diversification


Abstract: The heightened attention towards clean energy markets has been spurred by COVID-19 and geopolitical concerns in 2022. This study in­vestigates the persistence of the Nasdaq Clean Edge Green Energy, Wilder­Hill Clean Energy, S&P Global Clean Energy, iShares Global Clear Energy ETF, and Clean Energy Fuels stock indexes for the period from May 3, 2018, to May 2, 2023. The findings are mixed since long memories were observed throughout the tranquil period; therefore, the events of 2020 and 2022 did not accentuate persistence. Based on the findings, it can be inferred that the long-term predictability of clean energy markets has potential advantag­es for investors with a focus on environmentally sustainable investments. However, investors must be aware of market risks and volatility, especial­ly during periods of economic or political instability. To reduce risk and in­crease returns, investors should diversify their portfolios across different clean energy indexes and other asset classes.

9th International Scientific ERAZ Conference – ERAZ 2023 – Conference Proceedings: KNOWLEDGE BASED SUSTAINABLE DEVELOPMENT, hybrid – online, virtually and in person, Prague, Czech Republic, June 1, 2023

ERAZ Conference Proceedings published by: Association of Economists and Managers of the Balkans – Belgrade, Serbia

ERAZ conference partners: Faculty of Logistics, University of Maribor, Maribor (Slovenia); University of National and World Economy – UNWE, Sofia (Bulgaria); Center for Political Research and Documentation (KEPET), Research Laboratory of the Department of Political Science of University of Crete (Greece); Institute of Public Finance – Zagreb (Croatia); Faculty of Tourism and Hospitality Ohrid, University of St. Kliment Ohridski from Bitola (North Macedonia)

ERAZ Conference 2023 Conference Proceedings: ISBN 978-86-80194-72-1, ISSN 2683-5568, DOI:

Creative Commons Non Commercial CC BY-NC: This article is distributed under the terms of the Creative Commons Attribution-Non-Commercial 4.0 License ( which permits non-commercial use, reproduction and distribution of the work without further permission. 

Suggested citation

Chambino, M., Dias, R., & Morais da Palma, C. (2023). Clean Energy Stock Indexes: Trends, Fluctuations, and Implications for Investors. In V. Bevanda (Ed.), ERAZ Conference – Knowlegde Based Sustainable Development: Vol 9. Conference Proceedings (pp. 49-56). Association of Economists and Managers of the Balkans.


Choi, I. (2001). ìUnit Root Tests for Panel Dataî, Journal of International Money and Finance, 20, 249-272.

Dias, R., Chambino, M., & Horta, N. H. (2023). Long-Term Dependencies in Central European Stock Markets : A Crisp-Set. 2(February), 10–17. 

Dias, R., Heliodoro, P., Alexandre, P., Santos, H., & Vasco, C. (2021). Market Efficiency in Its Weak Form: the Pre-Covid and Covid Indonesia Analysis. 5th EMAN Conference Proceedings (Part of EMAN Conference Collection), October, 1–11. 

Dias, R., Horta, N., & Chambino, M. (2023). Clean Energy Action Index Efficiency: An Analysis in Global Uncertainty Contexts. Energies 2023, 16, 18. 

Dias, R., Pardal, P., Teixeira, N., & Horta, N. (2022). Tail Risk and Return Predictability for Eu­rope’s Capital Markets : An Approach in Periods of the. December.  

Dias, R., Pereira, J. M., & Carvalho, L. C. (2022). Are African Stock Markets Efficient? A Com­parative Analysis Between Six African Markets, the UK, Japan and the USA in the Peri­od of the Pandemic. Naše Gospodarstvo/Our Economy, 68(1), 35–51. 

Dias, R., & Santos, H. (2020a). Stock Market Efficiency in Africa: Evidence From Random Walk Hypothesis. 6th LIMEN Conference Proceedings (Part of LIMEN Conference Collection), 6(July), 25–37. 

Dias, R., & Santos, H. (2020b). The Impact of Covid-19 on Exchange Rate Volatility: an Econophys­ics Approach. 6th LIMEN Conference Proceedings (Part of LIMEN Conference Collection), 6(July), 39–49. 

Dias, R., Santos, H., Alexandre, P., Heliodoro, P., & Vasco, C. (2021). Random Walks and Market Ef­ficiency Tests: Evidence for Us and African Capital Markets. 5th EMAN Selected Papers (Part of EMAN Conference Collection), October, 17–29. 

Dias, R. T., Pardal, P., Santos, H., & Vasco, C. (2021). Testing the Random Walk Hypothesis for Real Exchange Rates (Issue June, pp. 304–322). 

Elie, B., Naji, J., Dutta, A., & Uddin, G. S. (2019). Gold and crude oil as safe-haven assets for clean energy stock indices: Blended copulas approach. Energy, 178. 

Farid, S., Karim, S., Naeem, M. A., Nepal, R., & Jamasb, T. (2023). Co-movement between dirty and clean energy: A time-frequency perspective. Energy Economics, 119.  

Guedes, E. F., Santos, R. P. C., Figueredo, L. H. R., Da Silva, P. A., Dias, R. M. T. S., & Zebende, G. F. (2022). Efficiency and Long-Range Correlation in G-20 Stock Indexes: A Sliding Windows Approach. Fluctuation and Noise Letters. 

Jarque, C. M., & Bera, A. K. (1980). Efficient tests for normality, homoscedastici­ty and serial independence of regression residuals. Economics Letters, 6(3).  

Papageorgiou, C., Saam, M., & Schulte, P. (2017). Substitution between clean and dirty energy in­puts: A macroeconomic perspective. Review of Economics and Statistics, 99(2). 

Pardal, P., Dias, R., Teixeira, N., & Horta, N. (2022). The Effects of Russia’ s 2022 Invasion of Ukraine on Global Markets : An Analysis of Particular Capital and Foreign Exchange Mar­kets.

Phillips, P. C. B., & Perron, P. (1988). Testing for a unit root in time series regression. Biometrika, 75(2), 335–346. 

Ren, B., & Lucey, B. (2022). A clean, green haven?—Examining the relationship between clean energy, clean and dirty cryptocurrencies. Energy Economics, 109.  

Ren, B., & Lucey, B. M. (2021). A Clean, Green Haven?- Examining the Relationship between Clean Energy, Clean and Dirty Cryptocurrencies. SSRN Electronic Journal.  

Santana, T., Horta, N., Revez, C., Santos Dias, R. M. T., & Zebende, G. F. (2023). Effects of interde­pendence and contagion between Oil and metals by ρ DCCA : a case of study about the COV­ID-19. 1–11.

Santos, H., Dias, R., Vasco, C., Alexandre, P., & Heliodoro, P. (2021). Has the Global Pandemic of 2020 Led To Persistence in the Share Prices of Large Global Companies? 5th EMAN Se­lected Papers (Part of EMAN Conference Collection), October, 1–15.  

Shahzad, S. J. H., Bouri, E., Kayani, G. M., Nasir, R. M., & Kristoufek, L. (2020). Are clean energy stocks efficient? Asymmetric multifractal scaling behaviour. Physica A: Statistical Mechanics and Its Applications, 550. 

Shen, S. M., & Wang, H. Y. (2023). Asymmetric Multifractal Analysis of the Chinese Energy Fu­tures and Energy Stock Markets under the Impact of COVID-19. Fluctuation and Noise Let­ters, 22(1). 

Teixeira, N., Dias, R. T., Pardal, P., & Horta, N. R. (2022). Financial Integration and Comovements Between Capital Markets and Oil Markets: An Approach During the Russian Invasion of Ukraine in 2022. Advances in Human Resources Management and Organizational Develop­ment, 240-261. 

Uddin, G. S., Rahman, M. L., Hedström, A., & Ahmed, A. (2019). Cross-quantilogram-based cor­relation and dependence between renewable energy stock and other asset classes. Energy Eco­nomics, 80, 743–759. 

Yang, L., Zhu, Y., & Wang, Y. (2016). Multifractal characterization of energy stocks in China: A multifractal detrended fluctuation analysis. Physica A: Statistical Mechanics and Its Applica­tions, 451. 

Yao, C. Z., Mo, Y. N., & Zhang, Z. K. (2021). A study of the efficiency of the Chinese clean energy stock market and its correlation with the crude oil market based on an asymmetric multifrac­tal scaling behavior analysis. North American Journal of Economics and Finance, 58. 

Zebende, G. F., Santos Dias, R. M. T., & de Aguiar, L. C. (2022). Stock market efficiency: An intr­aday case of study about the G-20 group. In Heliyon (Vol. 8, Issue 1).