It reacted pretty quickly, within an hour. But keep in mind what it gauges, the market’s expectation of 30-day forward-looking volatility:
What Is the Cboe Volatility Index (VIX)?
Created by the Cboe Global Markets (originally known as the Chicago Board Options Exchange (CBOE)), the Cboe Volatility Index, or VIX, is a real-time market index that represents the market’s expectation of 30-day forward-looking volatility. Derived from the price inputs of the S&P 500 index options, it provides a measure of market risk and investors’ sentiments. It is also known by other names like “Fear Gauge” or “Fear Index.” Investors, research analysts and portfolio managers look to VIX values as a way to measure market risk, fear and stress before they take investment decisions.