Trading term

What is Implied volatility?

Implied volatility (IV) is the market's forecast of how much a stock will move, backed out from option prices. High IV means expensive options and an expected big move; low IV means cheap options and expected calm. IV rises with fear and uncertainty, and it drives the time-value portion of every premium.

Implied volatility isn't measured from past prices (that's historical volatility) — it's implied by what traders are willing to pay for options right now. If option premiums are rich, the market is 'implying' a large expected move; if they're cheap, it expects calm. In effect, IV is the market's collective forecast of future movement, expressed as an annualised percentage. It's the single biggest driver of an option's time value, which is why the same option can cost wildly different amounts depending on the mood of the market.

IV is central to options trading because it tells you whether options are cheap or expensive relative to the expected move. Traders 'buy volatility' when IV is low (options are cheap) and 'sell volatility' when it's high (options are rich), regardless of direction. IV spikes before uncertain events (earnings, elections, crises) and collapses afterward — the 'volatility crush.' It also varies by strike, producing the 'volatility smile' or 'skew,' where out-of-the-money options (especially downside puts) carry higher IV because the market pays up for crash protection.

Implied volatility — the market's forecast
near the money — lowest IVlow strikes (downside puts)high strikes (calls)The volatility smile / skew: implied volatility varies by strike

IV is the expected move priced into options. Plotted across strikes it forms the 'smile / skew' — lowest at the money, higher at the wings, tilted up for downside puts (the market pays for crash protection).

For example

Two stocks both trade at $50 with a $50 call expiring in a month. The calm utility's call costs $1 (low IV — a small move expected); the biotech's call costs $5 (high IV — a big move expected, perhaps around a trial result). Same strike, same time — the difference is implied volatility.

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Why it matters to you

Implied volatility is what tells you whether an option is cheap or expensive, independent of direction — the closest thing options trading has to a 'valuation.' Skilled traders think in terms of IV as much as price: buying options when volatility is underpriced and selling when it's rich is an edge that direction alone can't provide.

⚠ High IV means expensive, not 'about to move'

It's tempting to read high implied volatility as a signal the stock will move — so buy options. But high IV means options are already expensive because a move is expected and priced in. Buying into elevated IV often means overpaying, then losing to the volatility crush even if the stock moves. High IV is a reason to be cautious about buying, not a green light.

Frequently asked questions

What is implied volatility?

Implied volatility is the market's forecast of a stock's future movement, backed out from current option prices and expressed as an annualised percentage. High IV means options are expensive and a big move is expected; low IV means cheap options and expected calm. It drives the time-value part of every premium.

What's the difference between implied and historical volatility?

Historical (or realised) volatility measures how much a stock has actually moved in the past. Implied volatility is forward-looking — the movement the market expects, inferred from option prices. Traders compare the two to judge whether options are cheap or expensive relative to how the stock typically behaves.

What is the volatility smile or skew?

It's the pattern where implied volatility varies by strike rather than being flat. Plotted across strikes, IV often forms a 'smile' (higher at both wings) or a 'skew/smirk' (higher for downside puts), because the market pays extra for out-of-the-money protection, especially against crashes.

Should I buy options when implied volatility is high?

Usually not, all else equal — high IV means options are already expensive because a move is priced in, and you risk a volatility crush after the event. Many traders prefer to buy when IV is low (options cheap) and sell when IV is high (options rich), independent of direction.

Related terms

Call optionA call option is a contract giving the buyer the right — but not the obligation — to buy an asset at a fixed 'strike' price before a set expiry date. Call buyers are betting the price will rise; their risk is capped at the premium paid, while the potential profit is open-ended.Cash-secured putA cash-secured put is an options strategy where you sell a put option while setting aside enough cash to buy the stock if you're assigned. You collect the premium as income; in exchange, you agree to buy the stock at the strike if it falls there. It's a way to get paid to buy a stock you want at a lower price.Covered callA covered call is an options strategy where you own 100 shares of a stock and sell a call option against them. You collect the premium as income; in exchange, you cap your upside at the strike. It's a popular way to generate income on shares you're happy to hold or sell.DeltaDelta measures how much an option's price moves for each $1 change in the underlying. A delta of 0.60 means the option gains about $0.60 if the stock rises $1. It ranges from 0 to 1 for calls (0 to −1 for puts) and doubles as a rough probability the option finishes in the money.
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