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- Semicondutores e geopolítica: o conflito Rússia-Ucrânia sob a ótica dos mercadosPublication . Sardinha, Luís Henrique Câmara; Sardinha, Luís; Martins, António Miguel Valente; Gouveia, Ricardo Nuno TeixeiraA presente dissertação analisa o impacto a curto prazo do início do conflito Rússia-Ucrânia nos retornos anormais das empresas da indústria dos semicondutores. Recorremos à metodologia de estudos de eventos para examinar uma amostra de 100 empresas, avaliando as variações nos preços dessas ações no período em torno do dia 24 de fevereiro de 2022 (início do conflito militar entre a Rússia e a Ucrânia). Os resultados indicam que, para a amostra completa, não se verificaram retornos anormais estatisticamente significativos. Contudo, ao dividir a amostra entre empresas europeias e não-europeias, observou-se que as empresas europeias registaram retornos anormais positivos e estatisticamente significativos, enquanto as empresas sediadas fora da Europa apresentaram resultados sem significância estatística. O teste para as diferenças de CARs entre essas duas subamostras confirma que as empresas europeias reagiram de forma distinta face às não-europeias, sugerindo que a localização geográfica desempenha um papel determinante na resposta ao conflito. A análise cross-section sugere ainda que certas características empresariais, como o ROA, Tobin_Q, percentagem de investidores institucionais e localização geográfica, influenciam a reação das empresas a choques geopolíticos. Esta dissertação contribui para a literatura ao colmatar a ausência de estudos sobre o impacto do conflito entre a Rússia e a Ucrânia na indústria dos semicondutores, uma indústria de elevada importância estratégica e económica. Trata-se do primeiro estudo a adotar uma abordagem quantitativa e a recorrer à metodologia de estudos de eventos para analisar este conflito neste contexto específico. Os resultados obtidos oferecem implicações significativas para investidores, gestores e decisores políticos, fornecendo uma visão aprofundada sobre a reação dos mercados a crises geopolíticas e destacando o papel das especificidades regionais e empresariais na formação dos retornos anormais
- Short-term market impact of 2024 US President elections and Trump-Zelensky meeting in defence industryPublication . Martins, António Miguel; Albuquerque, Bruno; Sardinha, Luís; Moutinho, Nuno; Martins, António Miguel; Albuquerque, Bruno; Sardinha, LuísThis study examines the short-term market effect of the US and European largest defence firms on the 2024 US presidential election (November 5, 2024) and the Trump-Zelensky meeting (February 28, 2025). By employing an event study methodology, our results show a positive and statistically significant stock price impact for both events. The results for the 2024 US presidential election are consistent with political business cycle theory. National elections in the arms- producing country drive a growth in sales revenues for defence firms, which tend to be higher when the Republican Party candidate wins the US elections. Our results also show the presence of heterogeneous abnormal returns between US and European defence firms around the Trump- Zelensky meeting, with European firms showing high and statistically significant positive returns while US firms show non-significant returns. This result is explained by the failure of security guarantees given by the US to the European countries and the awareness of the need for a rapid increase in military spending for self-defence purposes in Europe. This meeting reinforced the application of the principle of “Europe preference” in the acquisition of weapons. Finally, we conclude that stock market responses are reinforced or mitigated by firm-specific characteristics.
- 2024 U.S. presidential elections: an event study for U.S. and non-U.S. fossil fuel and renewable listed firmsPublication . Martins, António Miguel; Albuquerque, Bruno; Sardinha, Luís; Moutinho, Nuno; Martins, António Miguel; Albuquerque, Bruno; Sardinha, LuísThis study examines the short-term market effect of Donald Trump’ victory in the 2024 US presidential election on largest US and non-US listed worldwide fuel fossil and renewable firms. Employing an event study meth odology, we observe a negative and statistically significant stock price reaction for worldwide renewable listed firms. An analysis by economic zones reveals the existence of negative abnormal returns for renewable energy firms in the US, Europe, India and in the rest of the world. In the case of China, abnormal returns are not sta tistically significant. With respect to worldwide fossil fuel listed firms, abnormal returns are generally not sta tistically significant. However, regarding US firms, we observe positive and statistically significant abnormal returns. These abnormal returns are explained by the change of US energy policy (pro-oil and gas policy) and the expected cut in subsidies and lower profitability of investments in green energies. Finally, our study provide insight into which firm-specific characteristics emerge as value drives around US presidential elections. The results show that despite the change in environmental policy in the US, favourable to fossil energy, the stock markets reward firms with high environmental ratings. Overall, our results indicate that 2024 US presidential election, for implying a change in US energy policy, has relevant policy implications for energy listed firms.
- Presidential elections and secretary appointment: an event study for us biotechnology and drugsPublication . Martins, António Miguel; Albuquerque, Bruno; Sardinha, Luís; Moutinho, Nuno; Martins, António Miguel; Albuquerque, Bruno; Sardinha, LuísThe aim of this study is to analyse the effect of the 2024 US presidential election and the appointment of the US health secretary to the largest US listed biotechnology and drug firms. Using an event study methodology, we find that President Donald Trump’s election had no sig nificant impact on the industry. On the contrary, the results show statistically significant negative stock price reactions around the US health secretary appointment. The negative industry reaction to the US health secretary appointment is largely explained by his scepticism about vaccination and criticism about the high prices of drug prescriptions and margins in the industry. These re sults highlight the importance of top government position appointments, especially when such appointments eliminate much of the uncertainty regarding future government action in the in dustry and political uncertainty hypothesis. Finally, cross-section analysis reveals that the firms most penalized by the 2024 US presidential election and the appointment of the US health sec retary are those with the highest investments in R&D and capital expenditures. This could mean lower future investments in new vaccines or drugs, seriously harming society.
- The impact of wildfires on US insurance firms: evidence for the costliest wildfire in CaliforniaPublication . Martins, António Miguel; Albuquerque, Bruno; Sardinha, Luís; Moutinho, Nuno; Martins, António Miguel; Albuquerque, Bruno; Sardinha, LuísThis research study the short-term effect of the costliest wildfire in California (January 2025) on the US insurance industry. Employing an event study, we find a negative impact for Property & Casualty Insurance firms. This result agrees with damage hypothesis or claim effect, which argues that damage caused by catastrophic events results in a reduction of insurer market value due to insufficient ex ante premium to absorb the damage claims. Our study also shows that the level of loss, premiums, underwriting exposure, profitability, and leverage are significant determinants in the magnitude of the insurer’s stock market reaction.
- Artificial intelligence advancements and US nuclear energy deregulation are drivers of the short-term market returns of nuclear firms?Publication . Martins, António Miguel; Albuquerque, Bruno; Sardinha, Luís; Moutinho, Nuno; Martins, António Miguel; Albuquerque, Bruno; Sardinha, LuísThis study examines the short-term market effect of the US nuclear market deregulation an nouncements in an environment of increasing investments in AI, which demand clean energy. By employing an event study methodology, our results suggest that worldwide nuclear energy firms experienced a positive and statistically significant impact on stock prices for the announcements of investments in AI and nuclear market deregulation, particularly among larger firms and those located in the US. These findings support the cash flow hypothesis for AI and the deregulation hypothesis for the nuclear market. Practical implications of our findings are provided.