What Is Volga?
Last reviewed: by Options Analysis Suite Research.
Volga is the second-order Greek measuring vega convexity: how much vega changes per one-vol-point change in implied volatility. It is identical to vomma - the two names are used interchangeably across the literature. Volga is the structural exposure to vol-of-vol, and the central Greek for trades that bet on the volatility of volatility.
What Is Volga?
Take an option price V(S, sigma, t). Vega is ∂V/∂sigma. Volga (vomma) is ∂²V/∂sigma² - the second derivative with respect to volatility. Equivalently, volga is the rate at which vega changes as IV changes. For a Black-Scholes call:
volga = vega * d1 * d2 / sigma
where d1 and d2 are the standard BSM moneyness terms. Volga is largest at OTM strikes (where d1*d2 is positive and large in magnitude) and smallest at ATM (where d1 is near zero). This is structurally important: an ATM straddle has negligible volga; OTM strangles have substantial volga. Long-strangle = long volga.
Why Does Volga Matter?
- Pricing of vol-of-vol-sensitive trades. Risk-reversals, butterflies, strangles all carry volga. The volga component of P&L grows with the magnitude of vol moves; the vega-only attribution misses this.
- Stochastic-vol model calibration. Volga prices align with calibrated Heston nu (vol-of-vol parameter). Mis-pricing volga is the structural reason BSM cannot capture wing-strike pricing.
- FX-options market practice. The vanna-volga method (Castagna-Mercurio 2007) is the dominant FX-smile pricing convention; volga adjustments to BSM prices reproduce most of the observed wing-strike premium.
Volga vs Vega Convexity
Vega is concave in sigma at OTM strikes - it has a peak somewhere between ATM and deep-OTM, and falls off in both directions. Vega's slope is volga. For a long option position:
- At-the-money: volga is near zero; vega is at its peak (or near peak).
- OTM (or ITM) strikes: volga is positive (ITM & OTM put case is symmetric); a vol increase grows vega further from zero.
- Deep OTM: volga is positive but smaller in absolute terms because vega itself is small.
Long-strangle = long vega + long volga. As IV rises, the vega rises (positive volga effect), so dollar-for-dollar IV change produces non-linear P&L. This is the asymmetry that vol-of-vol traders harvest.
Worked Example
SPX 30-day OTM put at 4,800 strike with spot at 5,000. BSM calibrated values:
- Vega (sensitivity to a 1-vol-point IV change): $42 per contract
- Volga: $58 per contract per (vol point)^2
If IV moves from 14% to 17% (+3 vol points):
- Linear vega P&L: $42 * 3 = $126
- Volga (second-order) P&L: 0.5 * $58 * 3^2 = $261
- Total approx: $387
The volga contribution is the larger component on this OTM put for a moderate vol move. Linear vega-only attribution would understate the realized P&L by 2/3.
How Does Each Pricing Model Treat Volga?
- Black-Scholes: closed-form volga via the standard formula. Constant-vol assumption means BSM-volga underprices wing-strike convexity.
- Heston: stochastic-vol. Heston volga includes a covariance term between spot and vol that BSM omits. Heston typically prices wing volga higher than BSM, matching market data.
- SABR: per-expiration volga via the Hagan formula. The nu parameter (vol-of-vol) directly drives volga; calibrated nu sets the wing-pricing.
- Vanna-Volga method (FX practitioner standard). Adjusts BSM-implied vols using observed vanna and volga prices at three reference strikes (ATM, 25-delta call, 25-delta put). Reproduces FX smiles closely without requiring full stochastic-vol calibration. See Castagna-Mercurio (2007).
Volga in Trading Applications
- Long strangles. Long volga at OTM wings. Profits asymmetrically from vol increases; loses asymmetrically from vol decreases. Pair with vega-neutralizing front-month options to isolate volga.
- Butterfly spreads. Long the wings, short the body. Net long volga. Earns positive carry when IV stays flat; pays carry to be long volga when nothing happens.
- Risk reversals. Long OTM call, short OTM put. Volga-neutral if the call and put have matching volga; volga-biased otherwise. The volga structure of the risk-reversal explains the surface-skew dynamics.
- Vega-volga decomposition. Hedge vega first; the residual is your volga exposure. This is the practitioner workflow for clean vol-of-vol bets.
Limitations and Caveats
- Volga blows up at expiry. Like all higher-order Greeks, volga loses meaning in the last days before expiration where intrinsic value dominates.
- Cross-Greek interactions. Vanna and volga interact in vol-regime-change scenarios. Pure-volga isolation requires careful position construction.
- Model-dependent. Heston volga and BSM volga differ structurally, especially at the wings. Reporting "volga" without naming the model produces ambiguous numbers.
Related Concepts
Vomma · Vanna · Vega · Vol of Vol · Butterfly Arbitrage · Convexity · Greeks · Pricing Model Landscape
References & Further Reading
- Castagna, A. and Mercurio, F. (2007). "The Vanna-Volga Method for Implied Volatilities." Risk, January, 106-111. The canonical FX-smile pricing convention based on volga.
- Wystup, U. (2006). FX Options and Structured Products. Wiley. Practitioner reference for FX-options pricing including detailed volga/vomma treatment.
- Bossens, F., Rayee, G., Skantzos, N. S. and Deelstra, G. (2010). "Vanna-Volga Methods Applied to FX Derivatives: From Theory to Market Practice." International Journal of Theoretical and Applied Finance, 13(8), 1293-1324. Theoretical and practical foundations.
- Hagan, P. S., Kumar, D., Lesniewski, A. S. and Woodward, D. E. (2002). "Managing Smile Risk." Wilmott Magazine, September, 84-108. SABR formula including the volga (kappa^2 term) contribution to the smile.
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