CBOE SKEW Indexes
View The Press Release - CBOE to Begin Publishing Values for CBOE S&P 500 Skew Index
Introduction to CBOE SKEW Index ("SKEW")
The crash of October 1987 sensitized investors to the potential for stock market crashes and forever changed their view of S&P 500® returns. Investors now realize that S&P 500 tail risk - the risk of outlier returns two or more standard deviations below the mean - is significantly greater than under a lognormal distribution. The CBOE SKEW Index ("SKEW") is an index derived from the price of S&P 500 tail risk. Similar to VIX®, the price of S&P 500 tail risk is calculated from the prices of S&P 500 out-of-the-money options. SKEW typically ranges from 100 to 150. A SKEW value of 100 means that the perceived distribution of S&P 500 log-returns is normal, and the probability of outlier returns is therefore negligible. As SKEW rises above 100, the left tail of the S&P 500 distribution acquires more weight, and the probabilities of outlier returns become more significant. One can estimate these probabilities from the value of SKEW. Since an increase in perceived tail risk increases the relative demand for low strike puts, increases in SKEW also correspond to an overall steepening of the curve of implied volatilities, familiar to option traders as the "skew".
Options involve risk and are not suitable for all investors. Prior to buying or selling an option, a person must receive a copy of Characteristics and Risks of Standardized Options (ODD). Supporting documentation for claims, comparisons, recommendations, statistics or other technical data is available by calling 1-888-OPTIONS, sending an e-mail to email@example.com, or by visiting www.cboe.com/bxm.
Copies of the ODD are available from your broker, by calling 1-888-OPTIONS, or from The Options Clearing Corporation, One North Wacker Drive, Suite 500, Chicago, Illinois 60606. The information on this website is provided solely for general education and information purposes and therefore should not be considered complete, precise, or current. Many of the matters discussed are subject to detailed rules, regulations, and statutory provisions which should be referred to for additional detail and are subject to changes that may not be reflected in the website information. No statement within the website should be construed as a recommendation to buy or sell a security or to provide investment advice. The inclusion of non-CBOE advertisements on the website should not be construed as an endorsement or an indication of the value of any product, service, or website. The Terms and Conditions govern use of this website and use of this website will be deemed acceptance of those Terms and Conditions.