OneBeacon Professional Partners (OBPP) is independently operated, but affiliated with the OneBeacon Insurance Group. Its products are underwritten by OneBeacon companies. Established in February 2002, OBPP provides the professional liability platform for OneBeacon.

Rated A, "Excellent" by A.M. Best

A.M. Best Company, the leading provider of ratings, news, data and financial information for the global insurance industry, rates OneBeacon Insurance as “A, Excellent.” Best 's ratings are recognized worldwide as the benchmark for assessing insurers' financial strength and reflect an in-depth knowledge of the insurance industry developed during its 100-year relationship with the business. This is one reason why insurance industry professionals have consistently ranked Best's ratings number one in confidence, usefulness and understanding.

OneBeacon is rated "A" (Excellent), class XV, by A.M. Best, "A2" by Moody's, "A" by Standard & Poor's, and "A" by Fitch Ratings. The company is publicly traded on the New York Stock Exchange under the symbol "OB". White Mountains Insurance Group remains a principal owner.

Today, OneBeacon is a $1.9 billion business that is increasingly focused on specialized opportunities. In 2007, we started two new businesses – Specialty Accident and Health and OneBeacon Government Risks. We additionally hired a medical technology team that will provide custom solutions emphasizing product liability for medical devices. In Personal Lines we demonstrated our commitment to specialization through redesign of our package product that bundles auto, property and other coverages in a convenient single policy and bill. What’s more, we completed the transition of our New York business to Adirondack Insurance Exchange, a member-owned reciprocal organization offering its policyholders various non-insurance benefits.