I have a position in bio tech I am selling off as a scale order. In general the stock is pretty low volume. I noticed that when I am the lowest seller (my sell order shows up), when there are no other orders for a while exactly a single one of my shares sells at my ask every 3 minutes and 54 seconds with a .01 commission. Since the commission is so low I'm pretty indifferent, but I was curious if anyone knew why/what is going on?
HFT bots pinging for hidden orders in front of yours, as well as suspecting that you may be a whale with more orders than you’re showing. Also may be attempting to penny jump you, or playing other games they came up with. For example you may be giving them a way to easily get rid of test orders they’re placing to buy shares in front of you. http://www.beathft.com/?cat=21 “In addition, HFTs don’t like hidden orders because even though they can find out that they are at a certain level, they don’t know when they get cancelled or entirely filled and the free insurance is gone. They do like to use a trick against these orders, odd lot trades. Sometimes, in order to find out if there are hidden orders in an exchange/ECN they will send out orders for a tiny amount of shares (usually less than 50). When they discover the hidden liquidity, they can penny jump it or just keep sending odd lot orders to annoy and/or increase the trading costs of the trader behind it.”
I assumed it must be some type of bot, the exactly 234 seconds over and over again seemed too odd. Is there a specific defensive strategy I should pursue when I encounter this? My order wasn't hidden
Not sure, but I'd try to take some tips from here: http://www.beathft.com/?cat=21 "having a net of smaller sized hidden orders nicely distributed in different exchanges and ECNs can pretty much guarantee that you will get fills with less adverse selection than otherwise would be the case." You can also try increasing your sell price by 1-5 cents, while placing additional order(s) as hidden at a bit lower price - the price you actually want to sell at. (splitting qty between them)
I'm sorry, what exactly you are trying to defend against? Your commissions should not be affected by separate executions, unless you cancelling and resubmitting your order. You should be able to specify AllOrNothing if it really bothers you that much.