The reasoning that tariffs are affecting the stock market is founded on recent events and economic research. In April of 2025, the U.S. stock market crashed when there were new tariffs imposed because the Dow Jones Industrial Average dropped over 1,300 points and the S&P 500 dropped over 3%, adding to a loss in the market of over $3 trillion (Wikipedia). Economists have cited that such uncertainty related to tariffs makes it tougher for businesses to predict profits, manage supply chain costs, and plan for growth, ultimately discouraging investment and hiring (UC Riverside News). While there exists a contention that tariffs can actually help domestic firms in the long term, in the short run, the consequence has been investor confidence and stability loss, so yes, tariffs are detrimental.