Glossary term
Implied Volatility (IV)
Implied volatility is the volatility level implied by current option prices and option-pricing model assumptions.
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What Is Implied Volatility?
Implied volatility, or IV, is the volatility level implied by current option prices and option-pricing model assumptions. It is forward-looking because it reflects what the options market is pricing about possible future movement.
IV does not say whether the underlying security will rise or fall. It speaks to the expected size of movement, not the direction.
Key Takeaways
- Implied volatility is inferred from option prices.
- Higher IV usually means higher option premiums, all else equal.
- IV is forward-looking, while historical volatility is based on past movement.
- IV can rise before earnings, economic reports, or other uncertain events.
- Implied volatility is not a guarantee that the expected move will happen.
How Implied Volatility Works
Option-pricing models use several inputs, including underlying price, strike price, time to expiration, interest rates, dividends, and volatility. When the market price of an option is known, traders can solve for the volatility input that makes the model price match the market price. That solved-for value is implied volatility.
Because options prices change constantly, IV also changes. A rise in demand for options can increase option premiums and the implied volatility embedded in those prices.
Implied Versus Historical Volatility
Measure | Source | What it tells you |
|---|---|---|
Implied volatility | Current option prices | Market-priced expectation for future movement |
Historical volatility | Past price changes | How much the security actually moved in a prior period |
Realized volatility | Completed future period after it happens | What movement actually occurred |
How Options Traders Use IV
IV is often compared with the option's own past implied volatility and with realized volatility after the fact. That comparison can help traders evaluate whether the market priced too much or too little movement for a given event or time period.
Options traders use IV to judge whether option premiums are relatively expensive or cheap compared with history, comparable securities, or expected events. A high IV can make buying options more expensive and selling options more richly priced, but it can also signal greater risk.
IV also helps frame expected-move discussions. If the market expects a large move around earnings, that expectation may already be reflected in option premiums before the announcement.
What IV Can Mislead About
Implied volatility is not a forecast with certainty. It can overstate or understate the movement that actually occurs. It also does not capture every risk, such as liquidity, early exercise, assignment, spreads, or model assumptions.
A low IV does not mean an option is safe, and a high IV does not mean an option is automatically overpriced. The useful question is whether the premium is reasonable for the risk being taken.
The Bottom Line
Implied volatility is the volatility level embedded in option prices. It helps investors understand option premiums and market expectations, but it does not predict direction or guarantee the size of future moves.