VIX Volatility Index

The VIX measures the implied volatility of the S&P 500 Index, representing a kind of mood indicator for the US equity market. The higher the VIX level, the higher the expected price swings in the S&P 500 Index and the more nervous the market participants. The VIX is calculated by the Chicago Board Options Exchange (CBOE) for a continuous period of 30 days. Short-term CBOE options with a minimum term of nine days are used for this purpose.

The VIX is stated in annualized form. The formula “VIX x S&P 500 Index x square root of (30/365)” can be used to determine the expected volatility of the S&P 500 Index for the next 30 days. A VIX level of 15.0 percent and an S&P 500 Index of 1,650 points accordingly produce expected volatility of 70.96 points up and down for the next 30 days.

The VIX can thus provide a quick impression of the price swings that an investor should expect for an S&P 500 Index investment, based on the assessment of CBOE option traders.