Under the agreement, the domestic and foreign property-casualty subsidiaries of AIG will be placed in a special purpose vehicle (SPV), and AIG will purchase from AIU Holdings its equity interests in certain AIG affiliates.

Best said it views this restructuring as a "positive first step" in positioning the commercial insurance business as an independent global property-casualty organization and in preparation for a future public equity offering.

"The plan to rebrand the global property-casualty business was specifically designed to further distance the property-casualty insurance operations from AIG in identity and to enhance confidence among employees, brokers and customers," Best noted.

Specifically, the property-casualty business' interest in International Lease Finance Corp., United Guaranty Corp. and TRH Holdings (Transatlantic) will be transferred to AIG.

Best said the announcement of the restructuring alone has no immediate effect on these ratings because AIG will continue to own the businesses and because of "the considerable time that will be required to complete the planned divestiture."

But the rating firm said it is reviewing the ratings of AIG's domestic property-casualty operations and expects to formally announce the results of that review soon.

The companies involved in the unit being spun off include AIG Commercial Insurance Company of Canada; Audubon Indemnity Company and Audubon Insurance Company; AIG Casualty Company; National Union Fire Insurance of Louisiana; National Union Fire Insurance Company of Pennsylvania; and American Home Assurance Company.

Also included are companies that are part of the Lexington Insurance Pool, including AIG Excess Liability Insurance Company, Landmark Insurance Company, Lexington Insurance Company and AIG Excess Liability Insurance International.

Standard & Poor's said it views the AIG moves as "a positive development resulting in materially bolstered capital adequacy and enhanced quality of capital commensurate with the ratings on AIU's core commercial insurance group and foreign general property/casualty subsidiaries.

"This does not affect the ratings on AIG, but, we believe it does give a slight boost to the company's financial flexibility by improving its ability to facilitate noncore asset sales and accelerate its plans to offer to the public equity in the newly restructured AIU Holdings Inc.," S&P said.