S&P 500 plunges 6% to close its worst week since 2020 after China retaliates against Trump's tariffs

The S&P 500 plummeted 6% Friday, the Dow Jones Industrial Average plunged 5.5% and the Nasdaq composite dropped 5.8%. Markets are facing their worst crisis since the COVID crash after China matched President Donald Trump's big raise in tariffs in an escalating trade war.