how do you know who is buying and selling? in this instance you seem to insist that the 'client' bought and the 'MM' sold. does this occur if a client sells to the MM? how can you tell who is on each side of the deal? you are also assuming that the trades of the options and the stocks are 100% related - how do you know this. Maybe - just maybe, the stock ran up, the seller of the options was a huge institution and at the same time as selling the options they started selling stock, and forced the MM to try and get their delta ......just a possibility. but hey - why spoil a good confirmation story