VIX (CBOE Volatility Index)

What it answers

How nervous is the market right now? The VIX tries to put a single number on that. Run by the Chicago Board Options Exchange (CBOE), it distils the prices investors are paying for S&P 500 options into an estimate of how much the index is expected to swing over the next 30 days.

How it works

The VIX is not based on past price moves but on implied volatility, the volatility baked into current option premiums. When traders fear a big drop, they bid up the price of protective options, and the VIX rises. When complacency reigns, option premiums fall and the VIX drifts lower. That is why it is called the fear gauge: it tends to spike when stocks tumble and ebb when markets are calm, moving broadly inversely to the index itself.

The India equivalent

India has its own version, India VIX, published by the NSE. It uses the same CBOE methodology, adapted to the order book of Nifty 50 options, and measures the expected 30-day volatility of the Nifty rather than the S&P 500. Traders watch it closely because option premiums in the futures-and-options segment move with it.

A common rule of thumb among Indian traders: when India VIX climbs above roughly 20 it signals heightened fear and choppy markets, while a reading below about 15 suggests a calmer phase. India VIX has historically tended to sit somewhat higher than the US VIX in normal times, reflecting an emerging market's higher-volatility profile.

Why it matters

For option sellers, a high VIX means richer premiums but bigger risk; for buyers, it means costlier hedges. Long-term investors often treat extreme VIX spikes as contrarian signals, since peak fear has historically coincided with market bottoms. Either way, it is a quick read on the market's mood rather than a forecast of direction.