The VIX index, which shows the equity market's expectations for 30-day volatility and is often called Wall Street's "fear gauge," briefly soared 52% to 45.56, the highest since October 2020, after China imposed retaliatory tariffs on the U.S.

Long VIX-related ETFs surged in morning trading. UVIX rose 19%; UVXY rose 15%; VIXY and VXX rose 10%; VXZ rose 2%.