The report specifically states that many of the insurers with the greatest declines in net income from 2007 to 2008 were primarily financial and mortgage guaranty companies.

These lines represented less than 2 percent of the total P&C industry's average annual written premiums from 2002 through 2011 and are unique in that they carry a high level of exposure to mortgages and mortgage-related securities, the report cautioned.

The report further notes the P&C industry suffered heavy losses from catastrophes in 2007 and 2008. On the same week AIG's liquidity problems became known, Hurricane Ike struck Texas, for instance.

Additionally, P&C industry representatives interviewed by GAO said the market was in the midst of a soft cycle leading into the crisis.

GAO says, “While the crisis may have exacerbated certain aspects of this cycle, it is difficult to determine the extent to which underwriting losses were a result of the crisis as opposed to the existing soft market or the weather events of 2008.”

The report says the P&C combined ratio increased from 95 percent to 104 percent from 2007 to 2008, indicating that companies incurred more in claims and expenses than they received from premiums.

However, “the ratios during the crisis were not substantially different from those in the surrounding years,” the report says. Financial and mortgage guaranty insurers' combined ratios were particularly high and contributed to the elevated overall P&C ratios.

As an example of the limited impact of the crisis on P&C insurers compared to life insurers, aggregate stock prices of publicly traded P&C companies saw their lowest stock prices in February 2009, representing a 40 percent decline from the highest closing price in December 2007.

For life insurers, aggregate stock prices declined 77 percent for the same period, the report says.

P&C insurers did experience a steep decline in net income and capital during the crisis.

Net income dropped 94 percent from 2007 to 2008—although the industry's net income remained positive at $3.7 billion.

Realized losses of $25.5 billion contributed to the decline in net income. Seven P&C insurance groups, including six large groups and one smaller financial guaranty insurance group, accounted for 47 percent of the realized losses in 2008.

The realized losses resulted primarily from other-than-temporary impairments taken on certain bonds and preferred and common stocks.

At the same time, P&C insurers' capital declined 12 percent from 2007 to 2008, to $466.6 billion.

Although the reduction in net income was a major factor in the capital decline, unrealized losses of $85.6 billion also played a role, the GAO adds. The greatest unrealized losses occurred in common stocks and other invested assets, the report said. Three large P/C insurance groups accounted for 55 percent of the losses.