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Percorrer por autor "Teixeira, Nuno"

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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, Liliana
    Due 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.
    2025-02-25Artigo científico Acesso aberto Ver mais
  • Exploring the relationship between clean energy indices and oil prices: a ten-day window approach
    Publication . Dias, Rui; Galvão, Rosa; Cruz, Sandra P.; Irfan, Mohammad; Teixeira, Nuno; Gonçalves, Sidalina
    This 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.
    2024-08-12Artigo científico Acesso aberto Ver mais
  • MAMMALS in Portugal: A data set of terrestrial, volant, and marine mammal occurrences in Portugal
    Publication . Grilo, Clara; Afonso, Beatriz C.; Afonso, Filipe; Alexandre, Marta; Aliácar, Sara; Almeida, Ana; Alonso, Ivan Prego; Álvares, Francisco; Alves, Paulo; Alves, Paulo Célio; Alves, Pedro; Duarte, Beatriz; Duro, Virginia; Encarnação, Cláudia; Eufrázio, Sofia; Fael, António; Falé, João Salvador; Faria, Sandra; Fernandes, Carlos; Fernandes, Margarida; Lopes, Susana; Rosalino, Luís Miguel; Costa, Gonçalo Ferrão; Ferreira, Clara; Ferreira, Diogo F.; Ferreira, Eduardo; Ferreira, Joaquim Pedro; Ferreira, João; Ferreira, Diana; Fonseca, Carlos; Fontes, Inês; Fragoso, Ricardo; Rosário, Inês T.; López‐Baucells, Adrià; Franco, Claudia; Freitas, Tamira; Gabriel, Sofia I.; Gibb, Rory; Gil, Patricia; Gomes, Carla Patricia Jorge; Horta, Pedro; Gomes, Pedro; Gomes, Verónica; Rossa, Mariana; Grilo, Filipa; Amado, Anabela; Guedes, Américo; Guilherme, Filipa; Gutiérrez, Iván; Harper, Henry; Herrera, José M.; Hipólito, Dário; Infante, Samuel; Jesus, José; Russo, Danilo; Loureiro, Armando; Loureiro, Filipa; Lourenço, Rui; Lourenço, Sofia; Lucas, Paula; Magalhães, Ana; Maldonado, Cristina; Marcolin, Fabio; Marques, Sara; Marques, J. Tiago; Sá, Pedro; Amendoeira, Vitor; Marques, Carina; Marques, Paulo; Marrecas, Pedro Caetano; Martins, Frederico; Martins, Raquel; Mascarenhas, Miguel; Mata, Vanessa A.; Mateus, Ana Rita; Matos, Milene; Sabino‐Marques, Helena; Medinas, Denis; Amorim, Francisco; Mendes, Tiago; Mendes, Gabriel; Mestre, Frederico; Milhinhas, Catarina; Mira, António; Monarca, Rita I.; Monteiro, Norberto; Monteiro, Barbara; Salgueiro, Vânia; Monterroso, Pedro; Nakamura, Mónia; Silva Aparício, Guilherme; Negrões, Nuno; Nóbrega, Eva K.; Nóvoa, Miguel; Nunes, Manuel; Nunes, Nuno Jardim; Oliveira, Flávio; Oliveira, José Miguel; Santos, Helena; Palmeirim, Jorge M.; Pargana, João; Paula, Anabela; Araújo, Ricardo; Paupério, Joana; Pedroso, Nuno M.; Pereira, Guilherme; Pereira, Pedro F.; Pereira, José; Pereira, Maria João Ramos; Santos, Joana; Petrucci‐Fonseca, Francisco; Pimenta, Miguel; Pinto, Sara; Pinto, Nuno; Ascensão, Fernando; Pires, Rosa; Pita, Ricardo; Pontes, Carlos; Quaresma, Marisa; Queirós, João; Barbosa, A. Márcia; Queirós, Luís; Rainho, Ana; Graça Ramalhinho, Maria; Ramalho, Patrícia; Raposeira, Helena; Augusto, Margarida; Rasteiro, Francisco; Rebelo, Hugo; Regala, Frederico Tátá; Reto, Dyana; Jones, Kate E.; Ribeiro, Sérgio Bruno; Rio‐Maior, Helena; Rocha, Ricardo; Rocha, Rita Gomes; Rodrigues, Luísa; Román, Jacinto; Bandeira, Victor; Roque, Sara; Santos, João P. V.; Santos, Nuno; Santos, Sara; Santos, Carlos Pedro; Santos‐Reis, Margarida; Serronha, Ana; Sierra, Pablo; Silva, Bruno; Silva, Carla S. G. M.; Silva, Clara; Laborde, Marina I.; Barbosa, Soraia; Silva, Diogo; Silva, Luís P.; Silva, Ricardo; Silva, Carmen; Silva Júnior, Flavio Manoel Rodrigues; Sousa, Pedro; Sousa‐Guedes, Diana; Spadoni, Giulia; Tapisso, Joaquim T.; Oliveira, Luís Lamas; Teixeira, Daniela; Barbosa, Sérgio; Teixeira, Sérgio; Teixeira, Nuno; Torres, Rita T.; Travassos, Paulo; Vale‐Gonçalves, Hélia; Cidraes‐Vieira, Nuno; Merten, Sophie; Luz Mathias, Maria; Leitão, Inês; Barreiro, Silvia; Barros, Paulo; Barros, Tânia; Barros, Filomena; Basto, Mafalda; Bernardino, Joana; Bicho, Sara; Biedma, Luis Eduardo; Borges, Marta; Braz, Luis; Lemos, Rita; Brito, José Carlos; Brito, Tiago; Cabral, João Alexandre; Calzada, Javier; Camarinha, Cláudia; Carapuço, Mafalda; Cardoso, Paulo; Carmo, Mário; Carrapato, Carlos; Silva Carrilho, Maílis; Lima, Cátia; Carvalho, Diogo Filipe T. C. S.; Carvalho, Filipe; Carvalho, João; Castro, Diana; Castro, Guilherme; Castro, Joana; Castro, Luis Roma; Catry, Filipe Xavier; Cerveira, Ana M.; Cid, André; Linck, Paloma; Clarke, Rafael; Conde, Conceição; Conde, José; Costa, Jorge; Costa, Mafalda; Costa, Pedro; Costa, Cristina; Couto, André Pedro; Craveiro, João; Dias, Marta; Lopes, Hugo; Dias, Sofia
    Mammals are threatened worldwide, with 26% of all species being includedin the IUCN threatened categories. This overall pattern is primarily associatedwith habitat loss or degradation, and human persecution for terrestrial mam-mals, and pollution, open net fishing, climate change, and prey depletion formarine mammals. Mammals play a key role in maintaining ecosystems func-tionality and resilience, and therefore information on their distribution is cru-cial to delineate and support conservation actions. MAMMALS INPORTUGAL is a publicly available data set compiling unpublishedgeoreferenced occurrence records of 92 terrestrial, volant, and marine mam-mals in mainland Portugal and archipelagos of the Azores and Madeira thatincludes 105,026 data entries between 1873 and 2021 (72% of the data occur-ring in 2000 and 2021). The methods used to collect the data were: live obser-vations/captures (43%), sign surveys (35%), camera trapping (16%),bioacoustics surveys (4%) and radiotracking, and inquiries that represent lessthan 1% of the records. The data set includes 13 types of records: (1) burrowsjsoil moundsjtunnel, (2) capture, (3) colony, (4) dead animaljhairjskullsjjaws, (5) genetic confirmation, (6) inquiries, (7) observation of live animal (8),observation in shelters, (9) photo trappingjvideo, (10) predators dietjpelletsjpine cones/nuts, (11) scatjtrackjditch, (12) telemetry and (13) vocalizationjecholocation. The spatial uncertainty of most records ranges between 0 and100 m (76%). Rodentia (n=31,573) has the highest number of records followedby Chiroptera (n=18,857), Carnivora (n=18,594), Lagomorpha (n=17,496),Cetartiodactyla (n=11,568) and Eulipotyphla (n=7008). The data setincludes records of species classified by the IUCN as threatened(e.g.,Oryctolagus cuniculus[n=12,159],Monachus monachus[n=1,512],andLynx pardinus[n=197]). We believe that this data set may stimulate thepublication of other European countries data sets that would certainly contrib-ute to ecology and conservation-related research, and therefore assisting onthe development of more accurate and tailored conservation managementstrategies for each species. There are no copyright restrictions; please cite this data paper when the data are used in publications.
    2022Artigo científico Acesso aberto Ver mais
  • Testing the diversifying asset hypothesis between clean energy stock indices and oil price
    Publication . Dias, Rui; Galvão, Rosa; Cruz, Sandra P.; Irfan, Mohammad; Alexandre, Paulo; Gonçalves, Sidalina; Teixeira, Nuno; Palma, Cristina; Almeida, Liliana
    In 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.
    2024-11-01Artigo científico Acesso aberto Ver mais