this is the first time i've ever had this happen in 5 or 6 years of options trading.
i was short the aug 63 puts on RIO. it closed yest at 63.06 and never traded below that level all day. yes, i know that was cutting it a bit thin, but i didn't want to give up that final day theta and the bid/ask was stupidly wide for most of the day. it did close above 63 in any case.
so i was a bit shocked this morning to see the RIO options had been assigned. now i have to slap a collar around it quickly, i don't really want the position at this point.
not sure why this would happen? i always thought exercise notices have to be submitted to the OCH within an hour or so of the closing auction finishing. was the price action in the europe timezone sufficient in that one hour after ASX close such that a trader who was long the puts could determine that the stock was likely to fall today, and send the exercise notice in to the OCH? i don't trade international markets so i don't really know.
what raised my eyebrows was the fact that i had gotten assigned on 2 other (in the money) aug short option positions, but the broker's assignment notice (in my account management screen) for the RIO puts came in 6 hours after the other two. should i be suspicious of the broker pulling a swifty? ie. it's held in street name, so did they assign me against their own prop position after europe had been in session a few hours and it was looking quite likely the stock would fall today - even though they purportedly don't do this? unlikely i would have thought, as surely it would breach regulatory requirements. is there some other explanation? has anyone else had this happen before? wondering whether this is a normal occurrence, since as i said, i've never had this happen before in 5-6 years of trading ASX options.