Swiss Re estimates its losses from Hurricane Sandy at $US900 million ($860 million).

The figure, net of retrocession and before tax, is based on a total insured loss estimate of $US20-25 billion ($19-24 billion).

The reinsurer says its prediction is subject to uncertainty because of complex loss assessments, particularly relating to business interruption.

“The hurricane hit the densely populated northeast coast of the US,” Swiss Re Group Chief Underwriting Officer Matthias Weber said.

“This led to prolonged power outages, disruption to public transport and damage to other infrastructure that made recovery efforts very difficult. It also complicates the loss-assessment process.”

Swiss Re’s total insured loss estimate is higher than the $US16-22 billion ($15-21 billion) prediction from catastrophe modeller AIR Worldwide.

AIR had previously estimated insured losses to US onshore properties of $US7-15 billion ($6.7-14 billion).

The “significant increase” has been driven by a rise in estimated storm surge losses, according to AIR Principal Scientist Tim Doggett.

“This, in turn, is driven by a reassessment of the percentage of flood losses that will actually be paid, plus an improved storm surge footprint run against high-resolution industry exposure information,” Dr Doggett said.

The revision also follows a ruling that insurers cannot impose hurricane deductibles on homeowners’ policies because Sandy was downgraded to a post-tropical cyclone an hour before it made landfall.

In addition, New York Governor Andrew Cuomo issued a regulation requiring insurers to start investigating claims within six business days instead of the usual 15.