Management turmoil and sharp hurricane losses have prompted downgrades by major rating agencies of RenaissanceRe Holdings Ltd. Standard & Poor’s, A.M. Best, Fitch Ratings and Moody’s all lowered credit and financial strength ratings of the Bermuda-based company.

Earlier this week, company co-founder and chairman Jim Stanard resigned at the request of the board in connection with a Securities and Exchange Commission probe of alleged accounting wrongdoing.

Mr. Stanard received a “Wells Notice” from the SEC in July, stating his actions were under official scrutiny.

Also earlier this week, the company announced it had suffered third-quarter losses of $322 million, mostly stemming from $572.6 million in catastrophe losses.

In lowering the company’s financial strength ratings from “double-A-minus” to “A-plus,” S&P said it expects the company to record its first net loss in 2005 somewhere between $200 million and $300 million.

Catastrophe losses in both this year and last have raised questions about the company’s “concentrated exposures in certain zones,” S&P said.

“Upgrades are not expected in the near term even if earnings are above expectations because the potential increased volatility within RenRe’s business profile, and recent management changes, will require a long-term track record to support revising the ratings,” said Damien Magarelli, S&P credit analyst.

Moody’s said its insurance financial strength lowering to “A2″ from “A1″ reflects the fact that the departure of Mr. Stanard, and others, will have an unusually severe impact because of their unique knowledge about the company’s highly specialized business.

A.M. Best noted that as the market leader in global property catastrophe reinsurance, RenRe would take a harder hit than other companies from the last two hurricane seasons. But the company could benefit from the expected upswing in property catastrophe reinsurance pricing next year, Best said.

Both Fitch and Best downgraded the financial strength rating of RenRe’s leading reinsurance subsidiary, Renaissance Reinsurance, from “A-plus” to “A.”

Fitch also expressed concern about the management shake-up.

“Given the comparatively small size of RenRe’s senior management, and Fitch’s understanding of the active role played by Mr. Stanard, Fitch has historically viewed Mr. Stanard’s contributions as an integral part of RenRe’s success,” said the agency in a ratings bulletin.