Nov 12 - Fitch Ratings has assigned an 'A' Insurer Financial Strength (IFS) rating to OneBeacon Insurance Group, Ltd.'s (OneBeacon; 75% ownership by White Mountains) new operating company insurance subsidiaries, OBI National Insurance Company (OBIN) and Homeland Insurance Company of Delaware (HODE). The Rating Outlook is Stable. All other ratings of OneBeacon and its subsidiaries are not affected by this action. A full rating list is shown below. Fitch's rating action reflects the assignment of OneBeacon's group IFS rating to OBIN and HODE as core insurance affiliates. These recently established insurance entities were formed to write OneBeacon's ongoing business and will cede 100% to Atlantic Specialty Insurance Company, the group's primary ongoing insurance entity, through a quota share reinsurance agreement. This restructuring of business entities is being completed as part of the expected sale of OneBeacon's runoff business companies to Armour Group Holdings Limited (Armour).