Currently SPX monthly AM settled options are treated differently then all the other SPX options. Brokers hold orders that are displayed on the screen, so it is possible that you may not be filled for some time, even when paying the offer. Also if you are a "professional" your orders are routed to a broker, or if your order is over a certain size.
The CBOE announced that these monthly options will transition to the same Hybrid system that the SPXW's trade. You will now have multiple quoters for these options and you should see much tighter markets quoted once this transition takes place.
Should be good news if you trade the SPX
http://www.cboe.com/publish/regcir/rg17-136.pdf
The CBOE announced that these monthly options will transition to the same Hybrid system that the SPXW's trade. You will now have multiple quoters for these options and you should see much tighter markets quoted once this transition takes place.
Should be good news if you trade the SPX
http://www.cboe.com/publish/regcir/rg17-136.pdf