TY - UNPD A1 - Abdi, Farshid A1 - Kormanyos, Emily A1 - Pelizzon, Loriana A1 - Getmansky, Mila A1 - Simon, Zorka T1 - A modern take on market efficiency: the impact of Trump’s tweets on financial markets T2 - SAFE working paper ; No. 314 N2 - We focus on the role of social media as a high-frequency, unfiltered mass information transmission channel and how its use for government communication affects the aggregate stock markets. To measure this effect, we concentrate on one of the most prominent Twitter users, the 45th President of the United States, Donald J. Trump. We analyze around 1,400 of his tweets related to the US economy and classify them by topic and textual sentiment using machine learning algorithms. We investigate whether the tweets contain relevant information for financial markets, i.e. whether they affect market returns, volatility, and trading volumes. Using high-frequency data, we find that Trump’s tweets are most often a reaction to pre-existing market trends and therefore do not provide material new information that would influence prices or trading. We show that past market information can help predict Trump’s decision to tweet about the economy. T3 - SAFE working paper - 314 KW - Market efficiency KW - Social media KW - Twitter KW - High-frequency event study KW - Machine learning KW - ETFs Y1 - 2021 UR - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/59156 UR - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-591560 IS - May 10, 2021 PB - SAFE CY - Frankfurt am Main ER -