Vol of vol (volatility of volatility) is the volatility of the variance process itself. It is the diffusion coefficient on the variance state in Heston (sigma_v) and SABR (nu) and is directly observable in markets via VVIX.

How is vol of vol measured?

For SPX, the model-free measure is VVIX, which applies the VIX formula to VIX options. Model-implied measures come from Heston/SABR calibrations to listed option surfaces.

Why does vol of vol matter for traders?

Higher vol of vol fattens the tail of the implied distribution and richens deep OTM options. Long-volga positions (e.g., long straddles in long-dated tenors) benefit from rising vol of vol regardless of spot direction.

When does vol of vol spike?

Vol of vol spikes ahead of binary events, around macro surprise releases, and during liquidity stress. VVIX often leads VIX itself when uncertainty about the vol regime increases.

How does vol of vol differ from realized vol?

Realized vol measures the recent dispersion of underlying returns; vol of vol measures the dispersion of the volatility series. A market can have low realized vol but high vol of vol when traders price uncertainty about future regime changes.

What Is Vol of Vol?

Last reviewed: May 17, 2026 by Options Analysis Suite Research.

Vol of vol (volatility of volatility) is a measure of how much implied volatility itself tends to move. In standard SABR notation, vol-of-vol is the parameter nu (the diffusion coefficient on the stochastic-vol process dα = να dZ); in Heston, it is also nu (the diffusion coefficient on the variance process). Vol of vol is observable in markets through the VVIX index, which measures the implied volatility of S&P 500 implied volatility (VIX).

What Does It Measure?

Volatility is not a constant. The same underlying that has 15% IV today might have 22% IV next month and 12% the month after. Vol of vol quantifies this second-order movement: the extent to which the IV time series itself fluctuates. High vol of vol means IV is unstable and prone to large jumps; low vol of vol means IV is stable and mean-reverting around a steady level.

For options traders, vol of vol matters because it determines how much the value of a vega-neutral position can move from changes in vol structure even when spot is unchanged. Long-vol-of-vol positions (long OTM options on volatility, butterflies, calendars) profit when realized vol-of-vol exceeds priced vol-of-vol.

Worked Example

Consider a 30-day SPY option chain. Suppose ATM IV is 14% on Day 0. Over the next 30 days you might observe:

Day 5: IV rises to 16% on a small risk-off day
Day 12: IV drops to 12% as the rally continues
Day 18: IV jumps to 22% on a CPI surprise
Day 25: IV decays to 14% as the print is digested

The standard deviation of these IV changes (annualized) is the realized vol of vol. The market's pricing of this volatility-of-volatility shows up in OTM options of vol products themselves: VIX options trade at IVs that imply VVIX around 80-110% during normal regimes, spiking to 150-180% during stress. VVIX is literally the implied vol of S&P implied vol.

How Do Pricing Models Capture Vol of Vol?

Heston model: the parameter nu (often denoted σ_v or ξ in alternate notation) is the volatility of the variance process. Heston's variance follows dv = κ(θ - v)dt + ν√v dW, where κ is mean-reversion speed, θ is long-run variance, and ν is the vol-of-vol coefficient. Higher ν produces more curvature in the implied-vol smile (more excess kurtosis in the return distribution).
SABR model: the parameter nu (sometimes called the volvol parameter) is SABR's vol-of-vol; it is the diffusion coefficient on the stochastic-alpha process, distinct from alpha (the stochastic-vol level itself). Higher nu produces more smile curvature in the Hagan approximation.
Black-Scholes: assumes constant volatility, so vol of vol is implicitly zero. BS cannot price vol-of-vol risk; this is one of the structural reasons BS-implied IVs exhibit a smile.
Jump diffusion models: capture excess kurtosis through jumps rather than vol-of-vol directly. Bates (Heston + jumps) combines both mechanisms. Pure jump models produce smile from jumps without needing stochastic vol-of-vol.
Variance Gamma: captures kurtosis through the time-changed Brownian motion structure. The kappa (variance rate of the gamma subordinator) parameter plays a vol-of-vol-like role.

Why Does It Matter?

Three operational consequences flow from vol-of-vol:

Calendar spreads price vol-of-vol. A long calendar spread (sell short-dated, buy long-dated, same strike) is short gamma and long vega. Its P&L is dominated by changes in the term structure of vol, which is driven by vol-of-vol. Calendars profit when vol surface stays stable; lose when vol-of-vol expands.
Butterflies and condors are vol-of-vol structures. A butterfly buys curvature: it pays off if vol-of-vol expands beyond what is priced. Iron condors short curvature: they pay off if vol-of-vol stays compressed. Reading butterfly pricing across expirations tells you how much vol-of-vol the market is pricing at each horizon.
VVIX as a regime signal. Persistent VVIX above 110 signals elevated vol-of-vol regime where vol surfaces themselves are unstable. VVIX above 140 historically correlates with peak fear and is often a contrarian buy signal for vol products. VVIX below 80 signals complacency and tight vol surfaces; long-volatility positions are often most cheaply priced here.

Realized vs Implied Vol of Vol

Just as IV vs realized vol forms the volatility risk premium, implied vol-of-vol vs realized vol-of-vol forms a second-order risk premium. The market typically prices vol of vol higher than what is realized over time, which is why long-volatility strategies (long VVIX, long butterflies on average) suffer from negative carry. The systematic short-vol-of-vol trade (selling deep OTM VIX calls, selling butterflies) collects this premium with tail risk.

The challenge: vol-of-vol regimes shift abruptly. The same iron-condor strategy that collects steady premium for 11 months can lose 12 months of profit in one volatility-of-volatility expansion event (Aug 2015, Feb 2018, March 2020, Aug 2024).

Vol of Vol Across Asset Classes

Equity indices: S&P vol-of-vol (VVIX) typically 80-110%; spikes to 200% during stress.
Single stocks: vol-of-vol is dramatically higher than indices because earnings and idiosyncratic news drive sharp IV moves; single-stock VVIX-equivalent runs 120-200%.
Treasury options: vol-of-vol (MOVE index measures this for rates IV) typically lower than equities because rate-vol moves are more autocorrelated and less prone to jumps.
Crypto: vol-of-vol extreme; BTC IV can move 30 vol points in a day during liquidation cascades, making vol-of-vol-aware models essential.

Related Concepts

Volatility Smile · Volatility Skew · IV Crush · Term Structure · Volatility Risk Premium

References & Further Reading

Heston, S. L. (1993). "A Closed-Form Solution for Options with Stochastic Volatility with Applications to Bond and Currency Options." Review of Financial Studies, 6(2), 327-343.
Hagan, P. S., Kumar, D., Lesniewski, A. S., and Woodward, D. E. (2002). "Managing Smile Risk." Wilmott, 1, 84-108.
Gatheral, J., Jaisson, T. and Rosenbaum, M. (2018). "Volatility is rough." Quantitative Finance, 18(6), 933-949. Rough vol explains the high short-tenor vol-of-vol observed in equity surfaces.
CBOE. VVIX Methodology White Paper. The CBOE methodology for measuring vol of S&P 500 implied vol.

View the live SPY IV vs realized-vol history →

This page is part of the Pricing Model Landscape and the canonical reference set on options market structure. Browse all documentation.

As of the latest snapshot, SPY has an ATM implied volatility of 13.8%, IV rank 18% (percentile 43%); 20-day realized vol 15.1%. 25-delta skew is +4.4%, meaning OTM puts trade richer than OTM calls. The IV here is the input that pricing-model walkthroughs (Black-Scholes, Heston, SABR, local-vol) take as their starting point: each model decomposes the same observed quote into different latent dynamics (constant vol, stochastic vol, surface-fitted vol, etc.) which is why two models can agree on price but disagree on Greeks and on how vol will evolve.