I own shares of XYZ (with a decent unrealized gain). I also have a call spread on XYZ. It occured to me to consider what happens if for whatever reason I can't unwind the spread before expiry and both legs of the spread expire in the money -- which shares are considered to be sold to satisfy the assignment.
I assume that in the absence of a specific ID or a standing order ("sell highest basis shares first") the usual FIFO rule will have to apply.
So I talked to my broker (Fidelity) to ask about their mechanics of how to specify this. What the rep told me was: "After assignment but before settlement, contact Fidelity to specify which shares are to be used to satisfy the assignment."
I didn't argue about it with the rep, but that can't possibly be right, can it? Because that "ID" would be made after the sale and therefore is invalid, is it not?
Also, since the sale of shares persuant to the short leg assignment and the purchase of shares from the long leg exercise will happen at literally exactly the same time, does tax law even allow the purchased shares to be considered the shares being sold, since they weren't owned in any way prior -- even a second prior -- to the sale?