"The wildcards are the same today as they were on Sept. 12," Steven Dreyer, managing director of S&P's Insurance Ratings Service, said in the report.

"What was unknown then is still largely unknown," Mr. Dreyer said, highlighting, for example, the possibility that "liability losses could still go through the roof."

Other unknowns are the ultimate costs of business interruption claims, the report said, adding, however, with limited claims activity from offsite entities, the final figure is likely to be at the low end of initial estimates.

S&P said that net losses for insurers stand at roughly $30 billion currently, with reinsurers incurring about 60 percent of the total.

Commenting on the industry's resiliency, S&P said that while it had put 23 insurers or reinsurers on CreditWatch in the aftermath of the tragedy, eight were affirmed at the existing ratings. While the remaining entities were lowered, usually by one notch, factors other than terrorism contributed to the downgrades, according to the report.

"The catastrophe has nevertheless opened up cracks in the insurance business, even among the mightiest fortresses, as demonstrated by a Standard & Poor's CreditWatch action on "triple-A"-rated Munich Re in July 2002," the report said.

The report goes on to quote Mr. Dreyer, who believes that the events of Sept. 11 exposed the flaws in property-casualty insurance businesses, which are now being exposed further by the investment losses.

"They've lost their cushion, and they can't rebuild capital as fast as they would have liked," he said, referring to the cushion of healthy investment returns available in the past.

The report also reviews some of the positive effects of the tragedy on insurers, calling Sept. 11 "the defining event of the current hard market," and outlining some insurer strategies to become more adept at dispersing and analyzing risk.

"Suddenly, white collar workers in trophy office buildings can be more of a risk than mine workers," Mr. Dreyer commented in the report. He added that insurers are ceding less business to reinsurers?a strategy that could lead to better underwriting on the part of primary companies.

The report also includes discussions of government responses to terrorism in several European countries, and the effects of new capital on the industry.

Yesterday, Weiss Ratings in Palm Beach Gardens, Fla., also released a report on the effects of Sept. 11 on domestic insurers, putting the total impact for U.S. companies at $8.47 billion. The report also lists the net claims for 10 U.S. companies reporting the largest claims, according to Weiss' research.