What is the VIX?
Updated on August 24, 2026 · by Alex
The VIX is an index that measures how much volatility the market expects for the S&P 500 over the next 30 days. It is calculated from the prices of options on that index, and it is often called "the fear index."
The VIX does not measure what happened, but what the market expects to happen. It comes out of the prices people are paying for protection: when a lot of investors buy insurance against a fall, that insurance gets more expensive and the VIX rises.
Rough ranges, not rules:
Because it almost always moves in the opposite direction from the market. When the S&P 500 falls hard, the VIX jumps; when the market drifts calmly higher, the VIX deflates. That inverse relationship makes it a quick thermometer of the general mood.
It also has a striking feature: it reverts to the mean. Extreme panic does not hold for long. A VIX at 45 almost always comes back to normal levels within weeks, even if nobody can say when, or from what level of the market.
Believing that a high VIX means the market is going to fall. It does not say that. The VIX measures the expected size of the move, not its direction. A VIX of 35 says big moves are expected; they could be to the upside.
The second mistake, and a far more expensive one, is trying to invest in the VIX. The index itself cannot be bought: there are derivative products that track it, and those products lose value structurally when they are held over time, because of the mechanics of the contracts they use. They are short-term hedging instruments for professionals, not something to hold in a portfolio.
