What is the VIX?

The VIX — formally the CBOE Volatility Index — is the most-watched fear gauge in markets. It's a single number, updated continuously, that tells you how much movement traders expect in the S&P 500 over the next 30 days. When the VIX is low, the market is calm. When it spikes, something is breaking.

01 — SectionWhat it is

The VIX is calculated from the prices of S&P 500 options. Specifically, it's a weighted blend of out-of-the-money put and call prices, converted into an annualized expected volatility figure. The math is technical; the intuition is simple: when traders are paying up for insurance (puts) on the index, the VIX rises. When they aren't, it falls.

02 — SectionHow to read the level

• Under 13 — extremely calm, often associated with grinding uptrends.
• 13–20 — normal, the typical range in stable bull markets.
• 20–30 — elevated, the market is worried about something specific.
• 30–40 — outright stress, often around recessions, geopolitical shocks, or earnings of major firms.
• 40+ — crisis-level (March 2020, October 2008). Historically rare and usually short-lived.

03 — SectionWhy it moves

The VIX moves inversely to the S&P 500 about 80% of the time. When stocks fall, demand for downside protection rises, and so does the VIX. When stocks grind higher, the VIX drifts lower. The relationship breaks down in two situations worth knowing: melt-up rallies, when calls get bid up alongside the index, and exhaustion bottoms, when the VIX peaks before the index does. Some of the best buy signals in history have been VIX spikes above 40.

04 — SectionWhat it doesn't tell you

The VIX measures the magnitude of expected moves, not the direction. A high VIX doesn't predict a crash; it just says that whatever happens, the market expects it to be big. And it's a measure of the S&P 500 specifically — single-stock volatility (especially in meme stocks) can be wildly higher than the VIX would suggest. There are sister indices (VXN for the Nasdaq, RVX for the Russell 2000, single-stock vol surfaces) for that.