Allstate Corp suffered nearly $1.1 billion in catastrophe losses in the third quarter, the country's largest publicly traded home and auto insurer said on Thursday.

That is half of what Allstate lost in the second quarter, when parts of the United States were ravaged by record-breaking tornadoes, but nearly three times what it lost on disasters in the third quarter of 2010.

Of Allstate's $1.08 billion in total losses in the quarter, $500 million came from August's Hurricane Irene, which was the first hurricane to make landfall in the United States in three years.

It has not broken out the specific sources of its other losses during the period.

Allstate began disclosing monthly and quarterly catastrophe losses earlier this year, under pressure from analysts who wanted more disclosure on the company's exposures.