Quote from Dr._Bob:
Steve, thank you for verifying.
I think it is telling that not even you (as an IB staff member) were thinking that this would be the way the attached trailing stop behaves.
So, how was a client to know? I guess that a fair share of the complaints about malfunctioning trailing stops on this thread and elsewhere is due to this "feature" and quite a few $$$s have been wasted because of it.
I don't think it does make a lot of sense to design it the way it works now, but even if it does, it can only do good if users do understand the way it is supposed to function.
One reason I use attached orders is to get instant safety and to be protected in cases of connection failure. So waiting for an execution and then transmitting a trailing stop (via API or manually) is not a viable option for me.
Also, there are markets like Globex where you would enter with a limit order with a "generous" limit instead of a market order to get into the market faster (at least some people say so). Attaching a tight trailing stop (for scalpers) would require a lot of extra care.
And what is the benefit of having a trailing stop that trails the original limit used instead of the actual market price? If you are filled right at the limit (normal limit order) you get the exact same behavior as from a trailing stop that trails the actual market price. But if (for whatever reasons) you happen to be filled away from the limit, it wreaks havoc.
So, like alanm, I think this design should be reconsidered.