It's basically DoS attacks for other market participants. Basically all algo trading systems need to cancel/modify their limit orders to keep things relative t

It's basically DoS attacks for other market participants. Basically all algo trading systems need to cancel/modify their limit orders to keep things relative to the last traded price and the whole quote book. The way they maintain their own quote book is through some data feed's API. e.g., Processing messages via onBidChange(double price, int bidSize); suppose you send a million buy orders at $2.00 when the stock price is trading at $6.00; your orders won't get executed, but your competitor who's processing these messages will be busy processing these message. You ignore the bottom of the book because you know your own garbage orders while you focus on processing messages at the top of the book in case of a inter-market/equity-options-futures arbitrage opportunity arises for 200ms. Your competitor was busy processing your garbage orders for 200ms; he/she either can't arb the trade as fast as you can, or they are the mutual fund algo and they can't cancel/modify their VWAP limit orders fast enough, while you trade in and out 2000 shares for $0.01/share profit plus liquidity rebates in that 200ms.