PartnerRe Group and its members have been affirmed the financial strength rating (FSR) of A+ (superior) and issuer credit ratings of "aa-" of by AM Best Co.

Concurrently, Best has affirmed the ICR of "a-" and debt ratings of PartnerRe's parent, PartnerRe Ltd. The outlook for all ratings is stable.

These rating affirmations do not affect the ratings of Partner Re's recently acquired Paris Re subsidiaries, as these are currently separately rated.

The ratings reflect PartnerRe's excellent business profile, superior risk-adjusted capitalisation and very strong enterprise risk management practices. Its recent acquisition of Paris Re has further augmented the company's geographic scope and operating scale.

With a combined capitalisation in excess of $8 billion as of March 31, 2010, the group now ranks among the top five global reinsurance organisations, said the ratings agency. Best does believe there are some integration, operational and treaty overlapping risks associated with this transaction; however, given the relative size of Paris Re, these risks are manageable and are diminishing over time.

Despite PartnerRe's exposure to natural and man made catastrophes worldwide and its corresponding propensity for earnings volatility, PartnerRe's five-year average underwriting combined ratio of 91.4 percent compares relatively favourably to its peer group, said Best. This reflects the group's well diversified risk portfolio and consistently disciplined underwriting posture.

Offsetting these rating strengths is PartnerRe's moderately above average risk profile, Best added. As an assumer of risk, PartnerRe's earnings and capitalisation are subject to large shock losses including natural catastrophes.