AM Best Co. has assigned indicative ratings of "bbb" on senior debt, "bbb-" on sub-ordinated debt and "bb+" on preferred stock and trust preferred securities to OneBeacon Insurance Group Ltd. and OneBeacon US Holdings, Inc.'s recently filed $1 billion universal shelf registration.

OneBeacon Ltd. is the ultimate holding company for OneBeacon US Holdings. White Mountain Insurance Group Ltd. owns 75.1 percent (as of June 30, 2008) of OneBeacon Ltd.

The outlook assigned to the above ratings is stable.

The indicative ratings reflect the manageable financial leverage of OneBeacon Ltd., with debt-to-total capital of 32 percent through second quarter 2008 and coverage ratios over a three-year period that support the assigned debt ratings. Furthermore, the ratings reflect the group's improved operating performance over a five-year period and favorable capitalisation.

The operating companies of OneBeacon Ltd. are consolidated under the OneBeacon Insurance Group.

OneBeacon Group's financial strength rating of A (excellent) and issuer credit ratings of "a" are unchanged, and the outlook is stable.