Nov 7 - Standard & Poor's Ratings Services said today it assigned its 'BBB-' rating to OneBeacon U.S. Holdings, Inc. (OBH; BBB-/Stable/--) offering of $275 million of 4.6% senior unsecured notes due 2022. The senior notes will be guaranteed by OneBeacon Insurance Group Ltd. (NYSE:OB; BBB-/Stable/--), indirect parent of OBH. The existing ratings on OB and OBH remain unchanged. We understand the company will use the proceeds to redeem all of OBH's outstanding 5.875% $270 million senior unsecured notes due May 2013. On a pro forma adjusted basis, based on the financials as of third-quarter 2012 (ended Sept. 30), OB's consolidated debt leverage is expected to be in line with the current leverage. The debt leverage as of Sept. 30, 2012 was about 21%. Furthermore, the company's interest coverage ratio is likely to improve due to the lower expected coupon on the new debt. We expect the pro forma debt leverage and coverage ratios to remain supportive of the current ratings. RELATED CRITERIA AND RESEARCH Holding Company Analysis, June 11, 2009 RATINGS LIST OneBeacon U.S. Holdings Inc. Counterparty credit rating BBB-/Stable/-- Ratings Assigned Senior unsecured BBB- Complete ratings information is available to subscribers of RatingsDirect on the Global Credit Portal at www.globalcreditportal.com. All ratings affected by this rating action can be found on Standard & Poor's public Web site at www.standardandpoors.com. Use the Ratings search box located in the left column.