Hundreds of thousands, if not millions, of insurance claims will be filed because of Hurricane Sandy, and insurance companies will take a big hit as a result. So who will be most affected? 

Berkshire Hathaway (BRK.B 1.30%), Allstate (ALL 2.28%), and Travelers (TRV 1.74%) are the three top property and casualty underwriters in New York, so they will see a big impact. In the Northeast, we can bring AIG (AIG 1.70%) and Chubb (NYSE: CB) into the fold as top underwriters. With estimates likely to exceed $20 billion, these companies will be the big losers of Hurricane Sandy. 

The impact won't be devastating, but it will hurt the bottom line, especially if damages increase as the days go on. Insurers have had a relatively light storm season, but this single Frankenstorm could change everything, even for Berkshire Hathaway this quarter.

See more in the following video.