The U.S. property/casualty ("P/C") industry recorded a net underwriting loss of $23.5 billion for year-end 2017, according to preliminary results, mainly due to an estimated $52.9 billion in catastrophe-related insured losses, more than double that seen in the previous year.

This financial review is detailed in a new Best's Special Report, and the data was derived from companies' 2017 annual statutory statements received as of March 9, 2018, representing an estimated 96 percent of the total P/C industry's net premiums written.

The report stated that the 2017 catastrophes were the main driver for the industry's additional $18 billion in underwriting losses compared with the previous year. A.M. Best's $52.9 billion estimate of 2017 P/C industry catastrophe losses was a 109.8 percent increase over 2016, and dwarfed A.M. Best's previous industry record for estimated insured losses of $41.9 billion recorded in 2011, which included losses stemming from the Tohoku earthquake and subsequent tsunami in Japan, an active tornado season in the United States, and flooding in Thailand. A.M. Best also estimated that the catastrophe losses accounted for 10.0 points on the P/C industry's combined ratio, up from an estimated 4.9 catastrophe points in the prior year. The industry's reported combined ratio deteriorated 3.0 points to 103.8 from the prior year and was the worst of the last five years.