Make American Markets Gyrate Again
Abstract
This study looks at how Trump-related events affect financial markets by analyzing urgency scores and sentiment indicators based on topic models. We use all posts from Donald Trump's Truth Social account between 2022 and 2025 to see how his messages influence the volatility of S&P sector indices and other market indices. Three topic modeling methods are used: Latent Dirichlet Allocation (LDA), Joint Sentiment-Topic (JST), and a reversed version of JST (rJST). These models help classify topics and measure sentiment at the same time. Using the improved rJST model, we find clear shifts in sentiment across different topics, especially in 2024 and 2025. We identify high-volatility periods as key events and examine how Trump's posts during these times lead to abnormal returns. Our results show that different sectors react differently. Sectors such as Utilities, Materials, Information Technology, Industrials, and Financials are especially sensitive. Negative comments often cause stronger and longer market reactions than positive ones. This shows that analyzing sentiment by topic helps explain investor behavior. A 10-day event window gives the clearest picture of these market effects.