My broker told me (TDA) that options ITM get processed after the "After Market" trading is closed. A determination of the actual value of those calls is made based on the closing price at 8PM EST. So, even though you can't trade options after regular trading closes at 4 EST, the options are not converted until after 8 because there could be a material event (pr announcement) between 4 and 8 PM that might affect the pps value. Then, before excercising those calls, they need to confirm the call holder has the available funds, etc.. As far as seeing a big BOC, I don't know when we actually see that transaction as far as market totals are concerned.