What the VIX actually measures
The VIX is not a survey of investor opinion — it's derived mathematically from the prices of S&P 500 options. Options give investors the right to buy or sell at a fixed price. When markets are uncertain, investors pay more to insure their portfolios (buying put options), and that extra demand pushes option prices up. The VIX extracts the implied volatility embedded in those prices — in effect, it reads the market's own forecast of future turbulence.
Historical VIX spikes
| Event | VIX peak |
|---|---|
| Black Monday (October 1987) | ~150 (retroactive estimate) |
| Global Financial Crisis (2008) | 89.5 |
| Covid crash (March 2020) | 85.5 |
| Dot-com crash (2002) | ~45 |
| Eurozone crisis (2011) | 48 |
The VIX and the stock market: an inverse relationship
The VIX tends to move inversely to the S&P 500. When stocks fall, fear rises, and the VIX jumps. This relationship is not perfectly reliable — but it is consistent enough that the VIX is widely used as a real-time sentiment gauge. Some investors trade the VIX directly through ETFs or futures, betting on volatility itself rather than the direction of stocks.
"When the VIX is low, it's time to go. When the VIX is high, it's time to buy." — a traders' heuristic (not a rule, but a useful reminder)
What this means for you
The VIX is a useful barometer but not a trading signal. When the VIX is very high — meaning fear is extreme — history shows that future 12-month returns from equities have tended to be above average. But catching the exact peak in volatility is nearly impossible. The practical takeaway: extreme fear in markets is often a better time to be adding to your portfolio than pulling out of it.