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Lets say the bid is 49.98 and the ask is 50.01, the midpoint is 50. Is it possible to intentionally place limit orders at 49.99, have them filled, then place limit order at 49.98, have them filled, and continue placing lower and lower limit orders?

This is contrastingly different than short selling, where you are creating selling pressure, and hitting bids along the way.

This is just placing limits, getting filled by other people willing to sell at that price and repeatedly lowering your bid (and therefore the last quotations of the stock)

I'm not concerned about what is printed on the ask side of the book, because I know of PLENTY of computer algorithms that will only place an order once they see a price get filled on the tape.

George Marian
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CQM
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2 Answers2

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You can choose to place successively lower buy limit orders, but whether they get filled or not is not a given; it depends on whether sellers care to accept your bid.

In your example of a 49.98 / 50.01 spread, if you place a buy with limit of 49.99, it won't get filled (if the order reaches the market while still at 49.98 / 50.01) immediately, but will be added to the order book. By being added to the order book, the markets bid and ask become 49.99 / 50.01. Your order won't get filled until some seller places a market order or a sell limit order of 49.99 or less. No guarantee that that will happen, and even if it does, there's nothing to say that your follow-up buy at 49.98 will ever be filled. In fact, your 49.98 buy order queues up at the "end of the line" behind all previously pending 49.98 bids, since your order arrived after those other bids. Since the initial conditions you supposed had a 49.98 bid, such an order exists (or at least did exist; it might have been cancelled in the intervening moment.

Basically, your first buy at 49.99, if it happens, has essentially no influence on whether your second buy at 49.98 will happen. You can't expect to move the market lower by making a bid that is higher (49.99) than the existing best bid (49.98). Whatever influence your 49.99 order has is to raise the market's price, not lower it.

mgkrebbs
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The strategy could conceivably work if you had sufficient quantity of shares to fill all of the outstanding buy orders and fill your lower buy orders. But in this case you are forcing the market down by selling and reinforcing the notion that there is a sell off by filling ever lower buy orders. There is the potential to trigger some stop loss orders if you can pressure it low enough. There is a lot of risk here that someone sees what you are doing and decides to jump in and buy forcing the price back up.

Could this work sure. But it is very risky and if you fail to create the panic selling then you risk losing big. I also suspect that this would violate SEC Rules and several laws. And if the price drops too far then trading on the stock would be halted and is likely to return at the appropriate price.

Bottom line I can not see a scenario where you do not trigger the stop, net a profit and end up with as many or more stock that you had in the first place.