Martins, António MiguelAlbuquerque, BrunoSardinha, LuísMoutinho, NunoMartins, AntónioAlbuquerque, BrunoSardinha, Luis2025-12-162025-12-162025-111544-6123http://hdl.handle.net/10400.13/7506The 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.engStock returnsUS presidential electionsBiotechnology and drugsEvent study.Faculdade de Ciências Sociaisjournal article10.1016/j.frl.2025.108125