Endurance Specialty Holdings, a Bermuda-based specialty provider of P&C insurance and reinsurance, estimated its initial loss to be between $45m and $55m, before tax, related to the tornadoes that impacted Alabama, Arkansas, Georgia and Virginia states in April 2011.

The insurer said that the losses were predominantly driven by its catastrophe reinsurance book of business and were related to reinsuring regional homeowner and farm mutual insurance companies in the Southeast US.

According to the Endurance, the loss estimate is pre-tax and net of reinsurance and reinstatement premiums.

The loss estimate is largely derived from a combination of its proprietary catastrophe modeling, standard industry models, a review of in-force contracts and preliminary indications from clients and brokers.

Endurance Specialty Holdings writes property, casualty, healthcare liability, agriculture and professional lines of insurance and property, catastrophe, casualty, aerospace and marine, and surety and other specialty lines of reinsurance.