Investors are winding down another volatile session, with U.S. stocks on pace to wrap a losing week. Federal Reserve Chairman Jerome Powell fired a warning over tariffs, on Thursday President Trump clapped back calling for Powell to cut rates.

President Trump's unpredictable trade policies have pushed stock volatility up to its highest level in years, creating substantial uncertainty and, some say, opportunity on Wall Street.

The U.S. stock market has gone taken a nosedive since President Donald Trump announced tariffs for many countries around the world. Here's what to know.