Educational context: This article explains implied volatility for informational purposes. Nothing here is a trading signal, profit claim, or investment advice. GEX Levels sells options education tools and has a commercial interest in this subject. See our risk disclaimer.
What Implied Volatility Actually Is
Implied volatility (IV) is a number derived from options prices that tells you what level of future price movement is currently priced into the options market. It's expressed as an annualized percentage — an IV of 20% means the market is pricing in roughly a 20% range of annual movement for the underlying.
The key word is implied. IV is not calculated from historical price data. It's backed out of the Black-Scholes (or similar) pricing model by taking the market price of an option and solving for the volatility input that produces that price. In other words: given the option costs this much, what volatility assumption is embedded in that price?
This makes IV forward-looking. It reflects what option buyers and sellers collectively expect — or more precisely, what they're paying for — in terms of future uncertainty.
IV vs Historical Volatility: A Critical Distinction
Historical volatility (HV, also called realized volatility) measures how much a stock actually moved in the past — calculated from the standard deviation of returns over some lookback period. IV and HV measure different things:
| Dimension | Implied Volatility (IV) | Historical Volatility (HV) |
|---|---|---|
| What it measures | Future uncertainty, as priced in options | Actual past price movement |
| Direction | Forward-looking | Backward-looking |
| Data source | Options market prices | Underlying asset price history |
| Can diverge? | Yes — significantly, especially around events | |
When IV is substantially higher than HV, options are expensive relative to recent realized movement. When IV is lower than HV, options are cheap relative to what the stock has actually been doing. Neither condition is automatically tradeable — but the divergence tells you something about how the market is pricing uncertainty vs. recent experience.
Why IV Rises Before Earnings
The classic pattern every options trader learns: IV rises into earnings and collapses after. This is sometimes called the "IV crush" — and it follows directly from how IV works.
Before earnings, genuine uncertainty exists about the outcome. Option buyers pay up for protection or directional exposure. Sellers demand more premium to take the other side. IV — which is extracted from these elevated premiums — rises to reflect the higher price of uncertainty.
After earnings, the uncertainty resolves. The news is out. IV collapses because there's no longer the same event-driven uncertainty to price in. Premium falls sharply — even if the stock moves significantly in the expected direction, the IV component of the option's value has evaporated.
This is why traders who buy options before earnings based purely on directional conviction often lose even when they're right about the direction — the move was priced in and IV crush erodes the option's value.
IV Rank and IV Percentile: Context for IV Levels
IV is meaningless in isolation. A stock trading at 40% IV could be cheap (if it normally trades at 80%) or expensive (if it normally trades at 20%). Two measures provide context:
- IV Rank (IVR) — where today's IV sits relative to its range over the past 52 weeks. An IVR of 80 means IV is in the 80th percentile of its annual high-low range. High IVR: options are expensive relative to their own history.
- IV Percentile — the percentage of days over the past year when IV was below today's level. Similar in spirit to IVR but uses frequency rather than range.
Both measures help traders assess whether option premiums are elevated or compressed relative to the stock's own volatility history — rather than making the mistake of comparing absolute IV levels across very different underlyings.
How IV Connects to Gamma Exposure
IV and gamma exposure (GEX) are related but measure different structural things. Understanding the connection helps traders use both more effectively.
Gamma is the rate of change of delta — how quickly an option's directional exposure changes as the underlying moves. High-gamma options are more sensitive to price movement: their delta shifts more per unit of underlying movement. When IV is high, options have higher extrinsic value and the gamma structure of outstanding positions changes.
More practically: the IV environment affects how dealers hedge. In high-IV environments, option premiums are rich, dealers may have different net gamma exposures across the term structure, and the relationship between strikes shifts. GEX — which is calculated from open interest and gamma across strikes — gives you the structural consequence of those positions: where the hedging pressure concentrates and in which direction.
Reading IV tells you how expensive uncertainty has become. Reading GEX tells you how dealer positioning is likely to amplify or dampen actual price movement. Together, they give you a more complete picture of options market structure than either alone.
IV and the Volatility Surface
A single IV number is a simplification. In practice, every option on a stock has its own IV — varying by strike (the "volatility skew" or "smile") and by expiration (the "term structure"). The full picture is called the volatility surface.
Key structural features of the vol surface:
- Put skew — out-of-the-money puts typically carry higher IV than equivalent out-of-the-money calls, because demand for downside protection is structurally higher. The volatility smile is often actually a smirk.
- Term structure — near-term options often have higher IV than longer-dated ones when an event approaches (earnings, FOMC), and lower IV than longer-dated ones in calm periods.
- Strike-specific IV — the IV at different strikes tells you where the market is concentrating its uncertainty pricing. High IV at specific strikes can correlate with GEX cluster zones where dealer positioning is concentrated.
The GEX Levels Education Library covers the relationship between volatility surface structure and gamma positioning across 19 modules — from basic IV mechanics through advanced options-flow analysis.
Educational context only. This article explains implied volatility for informational purposes. Nothing here is a trading signal, recommendation to trade options, or claim about trading outcomes. Options trading involves substantial risk of loss. GEX Levels sells educational tools related to options market structure and has a commercial interest in this subject. See our full risk disclaimer.