Implied volatility (IV) is the market's forward-looking estimate of how much a stock's price is likely to move, expressed as a percentage and derived directly from current options prices — not from any prediction about direction, just magnitude of movement.
IV is one of the least intuitive concepts in options trading precisely because it isn't about whether a stock will go up or down — only about how much the market expects it to move, in either direction.
Implied vs Historical Volatility
| Historical (Realized) Volatility | Implied Volatility | |
|---|---|---|
| Measures | How much the stock actually moved in the past | How much the market currently expects it to move |
| Direction | Backward-looking | Forward-looking |
| Source | Calculated from past price data | Backed out of current options prices |
These two numbers are related but frequently diverge — IV often runs higher than recent historical volatility because the market is pricing in uncertainty around a specific known event, not just extrapolating the recent past.
How IV Affects Premium
All else equal, higher implied volatility means higher options premium — for both calls and puts. This is because a wider expected range of outcomes makes it more likely the option finishes with meaningful value, so the market prices that possibility in. When IV falls, premium falls with it, even if the stock price hasn't moved at all.
IV tells you nothing about direction. A stock can have very high implied volatility and still be equally likely (in the market's pricing) to go up or down — IV only speaks to the expected size of the move.
IV Crush Around Earnings
One of the most commonly discussed IV events is IV crush: implied volatility tends to rise into a known catalyst (like an earnings report) as the market prices in the uncertainty of an unknown outcome, then drops sharply right after the event, once that uncertainty resolves.
This matters because it means an option can lose significant value immediately after earnings even if the stock moves in the direction a trader expected — if the move isn't large enough to offset the IV crush, the position can still lose money. This is a widely documented pattern, not a guarantee, and it's exactly the kind of mechanic worth understanding fully before trading around scheduled events.
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