What Drives Index Options Exposures?* Timothy Johnson1, Mo Liang2, and Yun Liu1
Review of Finance, 2016, 1–33 doi: 10.1093/rof/rfw061 What Drives Index Options Exposures?* Timothy Johnson1, Mo Liang2, and Yun Liu1 1University of Illinois at Urbana-Champaign and 2School of Finance, Renmin University of China Abstract 5 This paper documents the history of aggregate positions in US index options and in- vestigates the driving factors behind use of this class of derivatives. We construct several measures of the magnitude of the market and characterize their level, trend, and covariates. Measured in terms of volatility exposure, the market is economically small, but it embeds a significant latent exposure to large price changes. Out-of-the- 10 money puts are the dominant component of open positions. Variation in options use is well described by a stochastic trend driven by equity market activity and a sig- nificant negative response to increases in risk. Using a rich collection of uncertainty proxies, we distinguish distinct responses to exogenous macroeconomic risk, risk aversion, differences of opinion, and disaster risk. The results are consistent with 15 the view that the primary function of index options is the transfer of unspanned crash risk. JEL classification: G12, N22 Keywords: Index options, Quantities, Derivatives risk 20 1. Introduction Options on the market portfolio play a key role in capturing investor perception of sys- tematic risk. As such, these instruments are the object of extensive study by both aca- demics and practitioners. An enormous literature is concerned with modeling the prices and returns of these options and analyzing their implications for aggregate risk, prefer- 25 ences, and beliefs. Yet, perhaps surprisingly, almost no literature has investigated basic facts about quantities in this market.
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