VIX, what it actually measures
The VIX, often called the "fear gauge," is the CBOE Volatility Index. It measures the market's expectation of 30-day forward-looking volatility on the S&P 500, derived from a weighted basket of SPX option prices.
What the VIX actually measures
The VIX is an annualized number expressed in percent. A VIX of 20 means the options market is pricing in roughly a 20% annualized standard deviation of S&P 500 returns over the next 30 days. To convert to a one-month expected move, divide by the square root of 12 (about 3.46). A VIX of 20 implies a 1-sigma monthly move of roughly 5.8%.
It is forward-looking, not historical. The VIX tells you what option buyers and sellers are collectively willing to pay for protection right now, not what volatility actually was last month.
How to read VIX levels
- Below 13: Complacency. Options are cheap, premium sellers earn less, hedges are inexpensive.
- 13 to 20: Normal regime. Most of the time the VIX lives here.
- 20 to 30: Elevated. Something is making the market nervous, earnings season, macro data, geopolitics.
- Above 30: Stress. Sharp selloffs, banking events, or a true panic. Premium is rich but realized moves are usually large too.
- Above 40: Crisis. Rare and almost always coincides with a major drawdown.
What the VIX is not
- It is not a directional indicator. A high VIX does not mean the market will fall further, only that the option market expects larger moves in either direction.
- It is not a single stock's volatility. Individual names can have IV much higher or lower than the VIX.
- It is not tradeable directly. You trade VIX futures, VIX options, or ETPs like VXX and UVXY, all of which have their own quirks (contango, decay).
Why options traders watch the VIX
The VIX sets the backdrop for every options trade. When the VIX is low, premium-selling strategies (iron condors, credit spreads, covered calls) collect less but face calmer markets. When the VIX is high, premiums are fat but realized moves often follow. Many traders use VIX regime as a filter: sell premium when VIX is elevated and mean-reverting, buy premium or stay defensive when VIX is rising fast.
Related terms: Implied volatility, IV rank, IV percentile, volatility term structure, vega
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