From what I have read with limit orders it sounds like these programs start fishing for orders to take a position in the opposite direction.
Something like this... There is a limit order for 10.03 to buy a stock on a break over $10.00. The stock is trading at 9.92. The predatory program starts looking for orders, finds the 10.03 limit order sells it to the buyer, and then goes short. So in a sense it drove up the price by just fishing for an order. Now the stock drove back down to 9.92.
The lucky trader with a limit order of 10.03 to buy on a break out was just a head fake and now sitting on a stock at 9.92 which appears will now sink because the break out was false.
Here is a comment regarding this from ThemisTrading on a White Paper (Toxic Equity) regarading this topic.
Quote:To illustrate, let’s use an institutional algo order pegged to the NBBO with discretion to pay up to $20.10. First, the predatory algo uses methods similar to the liquidity rebate trader to spot this as an institutional algo order. Next, with a bid of $20.01, the predatory algo goes on the attack. The institutional algo immediately goes to $20.01. Then, the predatory algo goes $20.02, and the institutional algo follows. In similar fashion, the predatory algo runs up the institutional algo to its $20.10 limit. At that point, the predatory algo sells the stock short at $20.10 to the institutional algo, knowing it is highly likely that the price of the stock will fall. When it does, the predatory algo covers. This is how a stock can move 10 or 15 cents on a handful of 100 or 500 share trades..