Thanks for the answers! By the way, are the number of contracts exercised published anywhere, or do you just have to guess at it from the change in open interest and trading volume?
OCC does a wheel to the firms - spins are based on OI at the firm. So if they have 100 to exercise they spin the wheel and it comes up firm A. A has 200 open so they get hit for the entire hundred. Most firms then allocate to customers based on FIFO - the firm has to have a written procedure in place. You mentioned nothing unusual in the after hours which would always be first expectation. The second, often surprisingly, is foreign exchange exposure. How did the stock open on Monday ?
Mine isn't like that, but yes, the brokerage can do either FIFO or some type of random (whatever they decided as their policy). Interesting, thanks. You don't think it went in my favor if I care this much? The stock was down a little premarket where I failed to cover, and then ran up a lot. I was short bias for my view so I just held my short and luckily I wasn't bought in before the stock came back down.
I'll frequently hedge a short ITM call by shorting ITM puts. There are also times when I'm short a put or call at expiration when the option expired ATM and I want to get assigned to either cancel out another position or to acquire shares. I wish the OCC had a way for traders who are short ATM options to indicate that they want to get assigned. Obviously, one can't assume that one will get assigned, but it would make sense to assign those traders who want to get assigned first before randomly assigning people who might not want to get assigned.
Thank you to everyone who responded. I never did figure out how or why this happened, but with the recent market down, I've been happy to hold my short position even if it didn't go my way initially after the assignment.
Shit you should be celebrating. if you got assigned and expired right ATM you got maximum squeeze out of that trade. Never assume anything with options you have to close out your position if you want to exit your obligations.