From The Street:
What a difference a couple of days make. Entering trading on Tuesday, the S&P 500 was within 1.3% of its all time high, and had remained within 10% of its peak for 662 straight days — the fourth-longest streak of tranquility, so-defined, since 1960.
Four trading days later, the index is down 6.3%, putting it 7.5% off its peak. The CBOE Volatility Index, also known as the VIX or “fear index,” tracks at-the-money and close-to-the-money front month S&P 500 option premiums, or “insurance” against a market correction. The VIX reflects the broader market’s perceived “tail risk,” or risk of a major correction.