A brief introduction of the MNX:

The MNX is a modified capitalization-weighted index composed of 100 of the largest non-financial securities listed on the Nasdaq Stock Market. It is 1/10th the value of the NDX index, so, for example, if the NDX index is at 1400, the MNX will be 140. It is European style, meaning that its options generally may be exercised only on the last business day before the expiration date should they become in the money. This is an advantage of this index, as it allows for the seller to wait out a move in the index, or to roll to another strike or month in order to avoid their option being in the money, and vulnerable to exercise. Trading in Mini-NDX options will ordinarily cease on the business day (usually a Thursday) preceding the day on which the exercise-settlement value is calculated (i.e. usually the 3rd Thursday of the month at market close). The exercise-settlement value for MNX options is computed by dividing the NDX settlement value by a factor of 10. The settlement values as well as much more in depth information can be found on the CBOE website.