Divisgood: I don't claim for a second to know all the technical underpinnings of all this, but by way of example, why don't you try the following: Enter an NATDF limit buy order with your U.S. brokerage. Use a safe/harmless number (1 share, for $1/share). Watch as your order gets instantly rejected after you "confirm" and try to put it through, with some sort of error message about an invalid symbol...
Bobdbeck: Yeah, spoke to the Global desk a couple times (last week). I think for you, the trick was that you bought it before the 5-to-1 reverse split was initiated. Now that the split has happened, supposedly new (U.S.) trades are restricted for a while. Maybe for grins, try the reverse of what I described above: sell 1 share, limit price of $100, and see if the open order is allowed.
On a separate note.. After listening to the SDRL conf call today, I was a little disappointed with what they had to say any time North Atlantic Drilling was mentioned. They had a couple opportunities to "give us a reason to believe" including an underhanded pitch from a concerned buyer who was worried that SDLP was getting priority on rigs over North Atlantic Drilling.. Personally, I would have liked to hear better re-assurance from management that NADL/NATDF isn't going to be the low-man on the totem pole, or some positive spin with more details for their growth plans.
Who knows, maybe they are saving a piece of news to coincide with the announcement re: the NYSE listing occurring.