The area of most concern is the "conditional trading' option...

The area of most concern is the "conditional trading' option that is available on online trading platforms. That is placing a buy or sell order at a certain price that does not appear in the buy/sell depth. Unfortunately I suspect that this information is available to 3rd parties who can manipulate a stock so as to trigger the conditional order prematurely which will get a lower or higher price than would be under normal trading. Making a few % this way over many stocks would add up to many $$$'s; it is another version of inside trading.