Where are "core trading session" and "opening and late session" defined in rule 7.10? That definition us the lynchpin for making the argument it's erroneous.
I already had an order to sell at $18.85. That order got cancelled automatically at the end of the normal trading day. I just had to go into that order and change the parameters that I wanted to change. In this case, it was only the quantity. Then I had to check the option to send that order after hours.
The earnings were the next day before the bell so I don't think that someone was trying to trick anyone. I think individuals via the ECN's can basically trade between each other after hours if they have the best bid/ask. No MM needed. Thats how I read it here. https://www.sec.gov/news/studies/ecnafter.htm
Ah, I see. Now this makes more sense. Does the platform have a SIM option or is there a SIM account you could use? Perhaps when changing an order, its possible that something goes wrong which doesn't usually creep up until there is a precise set of circumstances like a cancelled order getting changed after hours. Its quite possible like @vanzandt suggested that it might automatically change the price to best bid or something even if you didn't change it yourself. It would be really good for you to know exactly how the platform behaves in the same set of circumstances when you get someone to listen to you. In addition to this platform bug, it also seems like you have a good angle via the exchange and cancelling orders that seem fishy, so you might also win here. But if you're sure the price said what it said when you changed your order, and it was a limit order, then you may have a glitch because a limit order at 18.85 should never fill at the price it did. Either the platform changed the price, or changed limit to market.
There is only limit orders after hours. I don't think it's even possible to send a market order. When I want to modify a cancelled order, the last price stays the same. And believe me before sending that order I checked three times that everything was fine. There is no doubt in my mind that I was selling at $18.85. What happened after is a mystery.
Do you mean to say there are only limit orders after hours and that its not possible to send a market order? You obviously have a type since you said market twice.
Just to clarify, you are saying you submitted a sell limit at 18.85, and it was executed at 8.85? Or did you submit a market order because you thought there was a bid to support your trade? In earlier posts you mentioned what was bid at ARCA vs different venues and some 1000 shares that may have been before or after your execution. But you never said exactly what order you submitted.
That was a limit order to sell 4300 at $18.85. On my broker website, I saw there was 43x100 on the bid side. I wanted to hit that bid with my order. It appears that my broker sent my order to ARCA and the 43x100 wasn't on that platform. But I've no idea why the trade happened at $8.85 instead. Right after my trade, another 1000 shares were sold at the exact same price. And that order was cancelled 56 minutes later. But sadly mine wasn't.
When you say, "the last price stays the same" do toy mean last trade, or last entered...and are you 100% clear on this?