Wall Street opens cautious as tariff fears, Fed uncertainty, and key earnings reports shape investor sentiment.

Wall Street's indexes dropped on Monday after President Trump announced a 25% tariff on goods from Japan and South Korea, set to begin on August 1. The Dow Jones fell 456.55 points, the S&P 500 dropped 53.

With the tariffs set to kick in now on Aug. 1, the latest move by the White House amounts to essentially a four-week extension of its previous 90-day pause, wrote Tobin Marcus, an analyst at Wolfe Research.