European-style S&P 100 Index Options
Prior to 2001, S&P 100 Index Options (OEX) were American-style only, e.g., exercisable on any business day prior to expiration date. However, most other index options are European-style, meaning that they may be exercised only during a specified period of time just prior to its expiration.
In 2001, Chicago Board Options Exchange introduced European-style S&P 100 options (XEO), to give customers both American-style and European-style S&P 100 options. Some investors prefer European-style feature because it is not subject to the uncertainties involved with possible early exercise.
CBOE has a number of other contracts based on the S&P 100, including:
- OEX® S&P 100 Index Options -- American Exercise
- OEX® - S&P 100 Index LEAPS -- American Exercise
- WEEKLYS - Short-Term S&P 100 Index Options
- XEO® - European-style S&P 100 LEAPS
- QUARTERLYS - European-style S&P 100 (XEO) Index Options