RenaissanceRe Holdings Ltd. and its operating subsidiaries have had their financial strength and issuer credit ratings boosted by ratings agency A.M. Best.

Beast affirmed the financial strength ratings of A (Excellent) and upgraded the issuer credit ratings (ICR) to “a+” from “a” of Renaissance Reinsurance Ltd. and Renaissance Reinsurance of Europe (Dublin, Ireland).

A.M. Best also upgraded RenaissanceRe’s issuer credit rating on the company’s bonds and preferred shard and revised the outlook on all of the group’s ratings to positive from stable.

The FSRs of A (Excellent) and the ICRs of “a-” of DaVinci Reinsurance Ltd., Overseas Partners Cat Ltd. and the operating subsidiaries of Glencoe Group Holdings Ltd. remain unchanged.

“These rating actions reflect RenaissanceRe’s continued strong capitalization and — despite taking over $1 billion in losses from the 2004 and 2005 hurricanes — an historical track record (with the exception of 2004 and 2005) of exceptional underwriting performance and superior risk management techniques,” Best said.

“Earnings have been strong for 2006 year to date as a result of improved property catastrophe market conditions in the United States stemming from the 2005 hurricanes, resulting in growth in common equity of over 30 percent over the first nine months of 2006. In the ten years preceding 2004, RenaissanceRe generated returns on equity at the 20 percent range and greater.”

The ratings changes came after the departure of several senior managers including chief executive and founder Jame Stanard in connection with an investigation into RenaissanceRe’s use of finite reinsurance.

“As a market leader in global property catastrophe reinsurance, RenaissanceRe’s earnings remain exposed to high severity losses associated with catastrophic events on a worldwide basis such as those experienced in 2004 and 2005,” Best warned.

“Furthermore, RenaissanceRe’s specialty and individual risk businesses have experienced rapid growth in recent years with the individual risk unit taking significant losses from the 2004 and 2005 hurricanes.

“Nonetheless, these factors are somewhat mitigated by RenaissanceRe’s disciplined and analytical underwriting approach, sophisticated catastrophe modeling capabilities and the active monitoring controls over the individual risk business.”