Den norske Bank. International Swaps and Derivatives Association, Inc. Fifth Avenue, 27th Floor. Rockefeller Center. New York, NY USA. Oslo. Den norske Bank or DnB was a Norwegian bank that existed between and when it The state held a majority ownership in the bank in addition to its being listed on the Oslo Stock Exchange. In , DnB bought Vital Forsikring Headquarters : Bergen, Norway. Den norske Bank ASA, Postal address: NO Oslo, Norway - Visiting address: Stranden 21, Oslo. Telephone + 47 22 48 10 50 - Telefax +.