If you look at the mid or mark of an individual option in tos it is no longer the true mid. TOS told me that they are using some sort of arb free model to calculate the mid. It is complete bs that they did this without alerting customers. For the past several days I have been putting orders in at the mid and getting filled right away. In most instances, the new mid is not the "mid" and in some instances is wildly off from the true mid.