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nsomniyak

06/23/17 12:11 PM

#9347 RE: tedpeele #9346

What they do is put in a small order (the min amount required to "show" on L2 at the given price) that matches the top bid or low ask, then simply program their system as follows:

1. For orders at the same price, fill the in-house order first
2. Tag that in-house order with additional programming that indicates how much they really have/want at that price.

trding

06/23/17 12:34 PM

#9350 RE: tedpeele #9346

They do that just to get their foot in the door with your order, once say you put in a sell order for 50,000. They will put that on the ask, and keep the shares (naked). Then the trading algorithms take over (I know because they match any ask/bid instantly over anyone else, and move the price based on weighted average), so then they can walk down the price to try and cover at a cheaper price.
If that strategy goes against them, they can just dump shares back to you. I have also seen them put up big ask, and when I try to buy, the ask is removed. They can do this on the buy side also. So, they many not have an agenda to manipulate the price up or down, just manipulate our money into their hands, using our own orders against us. It is amazing any of us can make money on short term trades fighting against these optimized algorithms.