Feb 11 - Fitch Ratings has affirmed Unum Group Inc.'s (NYSE: UNM) holding company ratings, including the senior debt rating at 'BBB', as well as the Insurer Financial Strength (IFS) ratings of all domestic operating subsidiaries at 'A'. The Rating Outlook is Stable. See below for a complete listing of all ratings. KEY RATING DRIVERS The rating rationale includes UNM's overall operating performance which has remained strong despite a weak global economy; conservative investment portfolio; solid