Rating agency Moody's says second-quarter earnings among P&Ccarriers are likely to be pressured by losses paid on the May 20tornado in Moore. Okla.

In a report issued today, Moody's says the monster tornado—ratedEF5 on the Enhanced Fujita Scale, with winds of around 200mph—tracked through both residential and commercial areas of thecity, spelling potentially significant losses for both personal andcommercial property insurance lines.

The losses are credit negative for P&C insurers, saysMoody's.

However, despite the tornado's immensity—it was over two mileswide—Moody's says the tornado left a limited footprint making it“difficult to determine which insures will bear the brunt ofinsured losses.”

Catastrophe modelers' insured-loss estimates run between $2billion to more than $6 billion.

Moody's says at the top of the market share list for Homeownersinsurance is State Farm, followed by Farmers, Liberty Mutual,Allstate, USAA, Oklahoma Farm Bureau, Shelter Mutual, AAA NorthernCalifornia, Nevada & Utah, Travelers and Hartford.

On the commercial property side, Travelers leads in marketshare, followed by Liberty Mutual, CNA, Farmers, Zurich American,AIG, Assurant, Federal Insurance Co., Shelter Mutual andHartford.

Moody's says it expects “greater-than-normal damage tocommercial structures.”

As of Friday, State Farm says it received about 6,700claims—property and auto combined—and Farmers put its number at1,900—65 percent property—adding that it expects more.

Severe convective storms, including tornadoes, have amounted tosignificant accumulated losses for the P&C industry withinrecent years, says Moody's. Last year, insures suffered $15 billionin losses from these storms and more than $22 billion in 2011. Twoof the costliest connective storm events occurred in 2011 withmultiple tornadoes in Tuscaloosa, Ala., causing $7.5 billion ininsured losses and Joplin, Mo., producing $7 billion in losses.

While earnings will take a hit from the Moore tornado, Moody'sbelieves “underwriting margins will be more resilient compared to2010-2011” because of continued single-digit rate increases andmore restrictive terms and conditions. As part of their improvedunderwriting strategy, carriers have also non-renewed lessprofitable or loss-exposed business.

Reinsures have minimal exposure, notes Moody's, becausecatastrophe reinsurance protection “is typically structured torespond to relatively infrequent, high severity events such ashurricanes.” Tornadoes could trigger coverage for those primarycarriers that purchased aggregate reinsurance coverage againstannual loss accumulations from frequent weather events. However,coverage is expensive and does not “figure prominently in insurerrisk management programs.”