I regularly enter an order on TWS to buy/short at the market open, and attach a stop price. No problem when I am on the platform during, or just before the open. The challenge is when traveling, how to set this up pre-market, or even the evening before, such that a stop order a certain percentage away from the fill will be entered when the market opens, or shortly after. From my testing, IB can't handle a stop or trailing stop entered pre-market, without some problems. For example, the system will accept a trailing stop, but the trail will move with the price of the security pre-market, leaving open the possibility of getting taken out of the trade right at the open. And a trailing stop can't be entered as a conditional order, for example, to trigger at a certain time after the market open. (That would be ideal.) As regards a hard stop, impossible to set a stop price pre-market, or for example the night before, based on an open or filled price, because I don't have a crystal ball. And IB does not have an order type that will base a stop on an open or filled price. Yes, I know that I could program third party software to issue the orders, but that would require running my system when I'm not on the platform, which is something I don't do. So...if this is an issue you've faced, and if you've cracked the problem, please share.