Catastrophe losses set a new precedent for US insurers in 2004, according to estimates by ISO's property claim services unit.
Insured property losses arising from 22 catastrophic events reached a record $27.3bn in the US, it said.
More than 80% of losses stemmed from the extreme hurricane season. In the US, Florida hurricane claims resulted in the highest insured losses at $18.8bn.
ISO said the frequency of events since 1995 was less compared with earlier years, but insured losses have increased significantly.
