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Does VIX Truly Measure Return Volatility?

32 Pages Posted: 31 Aug 2014 Last revised: 17 Nov 2014

Victor Chow

West Virginia University

Wanjun Jiang

Guang Hua School of Management, Peking University

Jingrui Li

West Virginia University

Date Written: August 30, 2014

Abstract

This article demonstrates theoretically that without imposing any structure on the underlying forcing process, the model-free CBOE volatility index (VIX) does not measure market expectation of volatility but that of a linear moment-combination. Particularly, VIX undervalues (overvalues) volatility when market return is expected to be negatively (positively) skewed. Alternatively, we develop a model-free generalized volatility index (GVIX). With no diffusion assumption, GVIX is formulated directly from the definition of log-return variance, and VIX is a special case of the GVIX. Empirically, VIX generally understates the true volatility, and the estimation errors considerably enlarge during volatile markets. The spread between GVIX and VIX follows a mean-reverting process.

Keywords: Implied Volatility, VIX, Ex-ante Moments

JEL Classification: G10

Suggested Citation

Chow, Victor and Jiang, Wanjun and Li, Jingrui, Does VIX Truly Measure Return Volatility? (August 30, 2014). Available at SSRN: https://ssrn.com/abstract=2489345 or http://dx.doi.org/10.2139/ssrn.2489345

Victor Chow (Contact Author)

West Virginia University ( email )

P. O. Box 6025
Morgantown, WV 26506
United States

Wanjun Jiang

Guang Hua School of Management, Peking University ( email )

Beijing
China

Jingrui Li

West Virginia University ( email )

PO Box 6025
Morgantown, WV 26506
United States

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