http://www.cme.com/files/StopLogicClientImpactFinalPR.pdf The purpose of this document is to introduce the new GLOBEX Stop Order Logic functionality and describe the impact to CME customers. This new functionality has been implemented to prevent market spikes that can occasionally occur due to the continuous triggering, election and trading of Stop Orders. With this new logic, if traded prices exceed the predefined trade thresholds, the market will be put into a reserved state, which accepts orders but does not allow any trades to take place. Market Data 2.01 customers will see dissemination of the MG messages (Instrument Status), with the Instrument State set to âARâ to indicate that the market has been put into a reserved state. The M8 message (Theoretical Opening Price) reflects the calculated opening price while the instrument is in a reserved state, as well as when it reopens. Current Market Data 2.0 customers that parse, utilize, and incorporate the information from the MG and M8 messages into their order entry applications will not have to make any programming changes. The new Stop Order Logic is initially being implemented for GLOBEX Equity and Currency products. This functionality will be enabled for other GLOBEX products in a subsequent phase.