Using IB. And, for some reason, I cannot place a market-on-close on a MSFT call option; I tried on an expiration day when a call I wrote was in the money. Why? I wonder.
Kirribilli, My advice is to never, ever, ever use MOC or MOO orders with options. There are 15 option exchanges. There is no central auction market. You have no protection on bad prints. Many MM go wide at the close. Many brokers route those orders to a DMM that executes on a best efforts basis sometimes well before the close. IB might not accept these orders. NEVER, EVER.......ever Bob
Thanks for the insights. (I was trying to squeeze a couple cents out of what I hoped would be a PIN situation @ 100. I know, I know. Hey, I'm human.)