George Economou's Ocean Rig is shifting its corporate domicile to the Caribbean offshore tax haven of the Cayman Islands.
The Nasdaq-listed driller said the move from the Marshall Islands would be made from 15 April.
It gave no reason for the change, but said: "The change of corporate domicile will not affect the day-to-day business and operations of Ocean Rig."
Another Economou company, DryShips, said earlier this month it was selling its Ocean Rig shares.
DryShips