I think TDA has implemented a javascript in their web interface to "eavedrop" on your limit order (or it seems there's a monkey watching your every move. You raise the bid to buy, it also raises the bid a few cents above your price, vice versa if you lower the bid to get out, it'd also drop the bid ) They also have another trick on their web-based order entry UI. When you enter limit order to get out, like 50 cents above the current price, then "that stupid monkey" would come in to quickly change the limit price that you just entered back to the current price. If you don't attention, just enter the limit price, then quickly move the mouse over to hit the submit button, then your order will be executed at the current price (because the "stupid monkey" changes your price back to the current price so quick you wouldn't notice it). On several occassions, the javascript wouldn't let me to change the price while market was moving fast. sometimes I'd lose the chance to get out or seeing my profit was being vaporized. so I've switched to their two step order process that would require an additional step for confirmation on the price (to avoid those pesky javascript or if it was a real person, then you'd be a stupid monkey!
amtd has chat rooms. I find it suspicious that every day, you see the same number of 'members' in the rooms. one room has almost exactly 2000 EVERY day. I think they are padding the count with fake names.