Effective Monday, December 17, 2007, forITC 2.1 users only, CME Group will change the conditions under which “LAST” messages (Category “N” messages – Bid/Ask LAST update messages) will be generated for CME pit-traded options .   The new conditions under which “LAST” messages will be generated for CME pit-traded options are as follows:

a). There is a new bid that is higher than the LAST;

b). There is a new offer that is lower than the LAST;

c). There is any trade.

Currently, CME sends a “LAST” when:

 a). There is a New Bid that is higher than the LAST;

 b). There is a new offer that is lower than the LAST;

 c). There is a trade that is different from the LAST.

Pit-traded options market data messages are currently transmitted via Channel 3 of the MDP.