In general, Weeklys have the same contract specifications as standard options, except for the time to expiration, and offer the same continuous, two-sided quotes as standard options. As of March 24, 2006, CBOE offers four Weeklys classes:

SPX Weeklys: One-week, European-style options on the S&P 500 index with Friday A.M. settlement (last day of trading is a Thursday).
XSP (Mini-SPX) Weeklys: A smaller sized (1/10th) version of SPX Weeklys traded on the CBOE Hybrid Trading System.
OEX Weeklys: One-week, American-style options on the S&P 100 index with Friday P.M. settlement (last day of trading is a Friday).
XEO Weeklys: A European-style version of OEX Weeklys.
New series are listed each Friday and expire the following Friday, except that no new Weeklys are listed that would expire during the expiration week for standard options (the third Friday of each month). In other words, we do not list new Weeklys on the 2nd Friday of a month and do not trade Weeklys during the following, standard expiration week until Friday of that week.

Ticker symbols for Weeklys differ from traditional options contract symbols, with letters identifying the Weekly cycle. For example, the symbol for SPX Weeklys for the first week of the month is JXA, the symbol for the second week is JXB, etc.).

They are shorter term.

There is only one weekly expiration trading at any time.

There are few underlying issues which have weekly options.

I agree that near the money weekly options will have a large gamma risk.

WEEKLYS SHORT-TERM MINI-SPX INDEX OPTIONS

Exercise Style:
European. Short-term Mini-SPX Index options generally may be exercised only on its expiration date.

Last Trading Day:
Trading in short-term Mini-SPX Index options will ordinarily cease on the business day (usually a Thursday) before the date on which the options expire.

Expiration Date:
The Friday following the Friday of the listing of the options.

Settlement of Option Exercise:
Short-term Mini-SPX Index options are AM-settled. The exercise-settlement value, XSR, is calculated using the opening reported sales price in the primary market of each component stock on the expiration date. If the exercise-settlement value is not available or the normal settlement procedure cannot be utilized due to a trading disruption or other unusual circumstance, the settlement value will be determined in accordance with the rules and bylaws of the Options Clearing Corporation. The exercise-settlement amount is equal to the difference between the exercise-settlement value and the exercise price of the option, multiplied by $100. Exercise will result in delivery of cash on the business day following expiration.

WEEKLYS SHORT-TERM EUROPEAN S&P 100 INDEX OPTIONS (XEO)

Exercise Style:
European. XEO options generally may be exercised only on the last business day before expiration.

Last Trading Day:
Trading in short-term S&P 100 Index options ordinarily cease on the business day (usually a Friday) that the options expire.

Expiration Date:
The Friday following the Friday of the listing of the options.

Settlement of Option Exercise:
Short-term Standard & Poor’s 100 index options are PM-settled. The exercise-settlement value, OEX, is calculated using the last (closing) reported sales price in the primary market of each component stock on the last business day (the expiration date) or on the day the exercise notice is properly submitted if exercised before expiration. If the exercise-settlement value is not available or the normal settlement procedure cannot be utilized due to a trading disruption or other unusual circumstance, the settlement value will be determined in accordance with the rules and bylaws of the Options Clearing Corporation. The exercise-settlement amount is equal to the difference between the exercise-settlement value and the exercise price of the option, multiplied by $100. Exercise will result in delivery of cash on the business day following expiration.

WEEKLYS SHORT-TERM S&P 500 INDEX OPTIONS

Exercise Style:
European. Short-term S&P 500 Index options generally may be exercised only on its expiration date.

Last Trading Day:
Trading in short-term S&P 500 Index options will ordinarily cease on the business day (usually a Thursday) before the date on which the options expire.

Expiration Date:
The Friday following the Friday of the listing of the options.

Settlement of Option Exercise:
Short-term Standard & Poor’s 500 index options are AM-settled. The exercise-settlement value, SET, is calculated using the opening reported sales price in the primary market of each component stock on the expiration date. If the exercise-settlement value is not available or the normal settlement procedure cannot be utilized due to a trading disruption or other unusual circumstance, the settlement value will be determined in accordance with the rules and bylaws of the Options Clearing Corporation. The exercise-settlement amount is equal to the difference between the exercise-settlement value and the exercise price of the option, multiplied by $100. Exercise will result in delivery of cash on the business day following expiration.

WEEKLYS SHORT-TERM S&P 100 INDEX OPTIONS

Exercise Style:
American. Short-term S&P 100 Index options generally may be exercised on any business day before the expiration date.

Last Trading Day:
Trading in short-term S&P 100 Index options ordinarily cease on the business day (usually a Friday) that the options expire.

Expiration Date:
The Friday following the Friday of the listing of the options.

Settlement of Option Exercise:
Short-term Standard & Poor’s 100 index options are PM-settled. The exercise-settlement value, OEX, is calculated using the last (closing) reported sales price in the primary market of each component stock on the last business day (the expiration date) or on the day the exercise notice is properly submitted if exercised before expiration. If the exercise-settlement value is not available or the normal settlement procedure cannot be utilized due to a trading disruption or other unusual circumstance, the settlement value will be determined in accordance with the rules and bylaws of the Options Clearing Corporation. The exercise-settlement amount is equal to the difference between the exercise-settlement value and the exercise price of the option, multiplied by $100. Exercise will result in delivery of cash on the business day following the day the exercise notice is properly submitted.