The OCC rule is options will be automatically exercised if they are in the money based on the 4pm et closing price of the stock on its primary exchange. This would be the same across all brokers. In order for this not to occur, a DNE would need to be filled before 530pm et (individual brokers may have earlier cutoffs to meet this deadline.)
"a DNE would need to be filled before 530p" So now you are saying the broker WILL exercise before 530pm? I was told that you have to call them to getthem to exercise for the after hours price action. And this what I'm only talking about AFTER HOURS ACTION. I don't care what it closed at.
The OCC has a deadline of 530pm et to be notified that you are exercising an out of the money option (based on the 4pm et closing price) or cancelling an automatic exercise of an in the money option (based on the 4pm et closing price). Each broker will have different deadlines for their customers so that they can meet the 530pm OCC deadline. The cutoff time for IB, based on the previously posted link, is 430 pm et. The 4pm et closing price of the stock is what the automatic exercise is based on.
The question as exercise is kind of missing the issue. Adds/removes are done not to alter the spot if it's conventional a/r. The savvy desks played that and it doesn't always work. Desks are playing the a/r - often before it's even officially announced. Are you better off playing the a/r as opposed to the SPX?