Implied Volatility (IV)
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Definition
The volatility that, plugged into an option pricing model (Black-Scholes), makes the model price equal the option's market price. It is the market's forward-looking estimate of the underlying's annualized volatility over the option's life - a price quoted in volatility units.
How to read it
IV is not a forecast you compute from history; it is BACKED OUT of prices, so it reflects supply/demand for optionality plus a risk premium. High IV means options are expensive (favoring sellers), low IV means cheap (favoring buyers) - but 'high/low' only makes sense relative to the name's own history, which is why IV RANK and IV PERCENTILE (where current IV sits in its 1-year range) matter more than the raw number. IV is systematically higher than subsequently realized volatility on average (the variance risk premium), which is the structural tailwind for premium sellers and the tax on premium buyers.
How practitioners use it
Used as context among multiple indicators — never as a standalone signal to act.
Less common professional uses
There is no single IV: the SURFACE varies by strike (skew/smile) and expiry (term structure). Equity index puts carry higher IV than calls (negative skew) because of crash-hedging demand and negative spot-vol correlation - structure selection (risk reversals, ratio spreads, broken-wing flies) is fundamentally a trade ON that skew, not on a scalar IV. IV embeds the VARIANCE RISK PREMIUM: implied consistently exceeds realized volatility because sellers demand compensation for bearing variance risk, so the risk-neutral distribution from IV is wider and left-skewed relative to the real-world distribution - this is why risk-neutral POP understates a short-vol trade's true win rate but the edge is thin and tail-exposed. IV term structure inverts in stress (near-dated IV > far-dated) versus its usual upward slope; calendars/diagonals are direct bets on this term-structure shape, and an inversion signals the market pricing imminent event risk. The skew itself is a tradeable, mean-reverting quantity: risk reversals (25-delta call IV minus put IV) and the smile's convexity (butterflies) are priced factors, and selecting strikes without reading the current skew leaves the financing edge of structures like risk reversals unharvested.
Sources & provenance
Natenberg, 'Option Volatility and Pricing'; Sinclair, 'Volatility Trading'; Carr & Wu (2009) on the variance risk premium
This page is educational content published by Pachira Aquatica Global LLC. It is not investment advice and not a recommendation.