The US stock had gotten a bit ahead of the Oslo Bourse, where it was down less than 1%. Parity with Oslo is about $37, so if Oslo recovers, as it might given the Cypress news, etc., SDRL should also recover tomorrow. Since Oslo is hours ahead of New York, you can easily track what's happening even before the open with the symbol SDRLN.OL, and use Yahoo's currency converter.
I have been searching the web and called my broker - no one seems to have a clue. It might be somehow related to the Cypress problem. These types of moves always concern me since often a stock with this type of downmove is acting on info (perhaps inside) I don't have access to.