Implied vs historical volatility — what's the difference?

Historical (realised) volatility looks backward — how much a stock DID move. Implied volatility looks forward — how much the market EXPECTS it to move, read from option prices. The VIX is the best-known implied gauge.

Why the gap between them matters

When implied volatility sits well above recent realised volatility, the market is paying up for protection — often before an earnings report, a Fed meeting, or during a scare. When implied drops below realised, traders may be complacent about risk that is actually present. Example (illustrative): a stock that has bounced around at about 20% realised volatility for months suddenly shows 45% implied volatility with earnings next week — the 25-point gap is the market pricing in a possible big post-earnings jump.

The honest caveat

High implied volatility does not mean a stock will fall; it means the market expects a big move either way. Options get expensive right before known events and often cheapen the moment the news is out — the so-called volatility crush.

Live example: the VIX — the market's implied 30-day volatility for the S&P 500 — is currently around 18.8. That is the annualised volatility option prices are baking in right now; whether the index goes on to actually swing that much is its historical (realised) volatility, known only after the fact.

How this connects to Quantustik

Implied and historical volatility are standard public concepts, not a Quantustik edge. Our forecasts express expected movement through a calibrated confidence band whose width widens when uncertainty rises — the same instinct implied volatility captures, expressed as an honest, backtested price range rather than an options quote. None of this is investment advice.

Frequently asked questions

What is the difference between implied and historical volatility?

Historical volatility is backward-looking — how much a stock actually moved. Implied volatility is forward-looking — how much the market, via option prices, expects it to move. The VIX is a well-known implied-volatility gauge.

Does high implied volatility mean a stock will go down?

No. Volatility measures the expected SIZE of moves, not their direction. High implied volatility means the market expects a big move either way, commonly around earnings or macro events.

Why do options get more expensive before earnings?

Because implied volatility rises ahead of a known event that could cause a large move. Once the news is out and uncertainty resolves, implied volatility often falls and those options cheapen.

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Related terms

Educational research only — not investment advice.