This thesis investigates how the U.S President’s Twitter mentions of individual companies’ investment announcements influence the short-term price of their stock. By assuming that the President’s comments on a company’s plans should be incorporated by markets as new information, testing the Efficient Market Hypothesis assumption that the markets incorporate all new information, the thesis seeks to contribute to a new, unexplored and growing, research field. This thesis utilizes a qualitative analysis method, studying Twitter mentions on the topic of Trump’s Tax Reform. The data in this thesis is derived from the President’s personal Twitter-account, company announcements, stock price charts, and the Standard & Poor’s S&P500 Index. To conclude, this study finds that although the President’s Twitter comments may signal his public approval of a company and its plans, it appears that any market reaction is only short-term, and that as the market incorporates additional information it returns to an informed state in terms of stock valuations. This study suggests that there are few observable indicators that Trump’s positive mentions on Twitter causes any significant market reaction.

The U.S. has enjoyed global hegemonic power for over 70 years and even more so after the fall of the Soviet Union. However, some political scientists argue that it is descending and the evidence lies in the increasing power of China. An imbalance of power in the international structure has the ability to result in different outcomes. The realist theory suggests that a conflict between the U.S. and China is unavoidable, the liberal theory suggests that the economic dependency between the two makes conflict less possible, while the constructivist theory suggests that the outcome depends on the reaction of the leaders and social change. This study asks what the reaction of the President of the U.S. is to the rise of China to find out the result of this hegemonic power imbalance. By using discourse analysis, this study has analyzed the remarks of President Trump from the period of January 2017 to November 2017 in search of his reaction to the rise of China. The results of this study show that President Trump divides the world in two parts making the U.S. the protagonist and the rest of the world, including China, the antagonist in his discourse as his reaction. Due to this reaction, Trump takes nationalistic and protectionist measures against China.

Foreign policy of Trump's administration: Withdrawal from the Paris Accord through the lens of two-level game theory Abstract Foreign policy of President Donald Trump has been a point of enquiry of many scholars so far. In the literature, we can observe a great diversity in opinions that attempt to explain his motivations in certain specific foreign policy actions. The main focus of this diploma thesis is laid on the withdrawal from international treaties, namely the Paris Accord from 2015. In this idiographic case study, we utilize the theory of two-level games by Robert Putnam which enables us to analyze the link between the domestic level of the decision to withdraw the international treaty. By identifying veto players in the U.S. political system, more concretely in its environmental policies, we were able to uncover the underlying notions behind the decision. Veto players in our case were the Congress with Republican and Democratic party, electoral impetus covering the general public opinion and new actors entering the public debate (private companies and states). Alternatively, we described the President's and his administration distinctive motivations. The thesis provides a new insight into the politics of the decision to withdraw from the Paris Accord. As per our findings, the electoral impetus is...