Open Access Letter

Asymmetric Efficiency: Contrasting Sustainable Energy Indices with Dirty Cryptocurrencies

by Rosa Galvão a,*  and  Rui Dias a, b
Accounting and Finance Department, Instituto Politécnico de Setúbal, Setúbal, Portugal
Center for Studies and Advanced Training in Management and Economics (CEFAGE), University of Évora, Évora, Portugal
Author to whom correspondence should be addressed.
FEL  2024, 22; 3(1), 22;
Received: 20 November 2023 / Accepted: 3 December 2023 / Published Online: 16 January 2024


This paper examines the efficiency, in its weak form, of the clean energy stock indices, Clean Coal Technologies, Clean Energy Fuels, and Wilderhill, as well as the cryptocurrencies classified as "dirty", due to their excessive energy consumption, such as Bitcoin (BTC), Ethereum (ETH), Ethereum Classic (ETH Classic), and Litecoin (LTC), from January 2020 to May 30, 2023. In order to meet the research objectives, the aim is to answer the following research question, namely whether: i) the events of 2020 and 2022 accentuated the persistence in the clean energy and dirty energy indices? The results show that clean energy indices such as digital currencies classified as "dirty" show autocorrelation in their returns; the prices are not independent and identically distributed (i.i.d). In conclusion, arbitrage strategies can be used to obtain abnormal returns, but caution is needed as prices can rise above their real market value and reduce trading profitability. This study contributes to the knowledge base on sustainable finance by teaching investors how to use forecasting strategies on the future values of their investments.

Copyright: © 2024 by Galvão and Dias. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) (Creative Commons Attribution 4.0 International License). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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ACS Style
Galvão, R.; Dias, R. Asymmetric Efficiency: Contrasting Sustainable Energy Indices with Dirty Cryptocurrencies. Financial Economics Letters, 2024, 3, 22.
AMA Style
Galvão R, Dias R. Asymmetric Efficiency: Contrasting Sustainable Energy Indices with Dirty Cryptocurrencies. Financial Economics Letters; 2024, 3(1):22.
Chicago/Turabian Style
Galvão, Rosa; Dias, Rui 2024. "Asymmetric Efficiency: Contrasting Sustainable Energy Indices with Dirty Cryptocurrencies" Financial Economics Letters 3, no.1:22.
APA style
Galvão, R., & Dias, R. (2024). Asymmetric Efficiency: Contrasting Sustainable Energy Indices with Dirty Cryptocurrencies. Financial Economics Letters, 3(1), 22.

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