Not sure if any one else noticed, but the Cboe changed the way customer orders are filled in the SPX. It used to be that there was customer priority, so if your order was marked as customer, you got priority over all other traders. This was especially useful in tighter markets or if you changed the market. Now the orders are filled on a pro-rata basis (based on the size of your bid or offer). So if the market is 1.40 -1.55 and you place an order to sell 1 at 1.50 and a market maker matches your offer for 200, you basically wont get filled unless the entire offer is taken out.
On the plus side, this was done when they introduced their new hybrid system for spx quotes so there are now multiple quoters and tighter markets.
On the plus side, this was done when they introduced their new hybrid system for spx quotes so there are now multiple quoters and tighter markets.