Amlin, the biggest listed British insurer in the Lloyd's of London market, said it sold $150m (£95m) of catastrophe bonds to protect itself against potential losses from US earthquakes and hurricanes and European storms.
The bond issue, carried out through Bermuda-based vehicle Tramline Re, is double the $75 million of cover a source said Amlin originally sought during the marketing stage.
"The protection afforded under this bond will complement our traditional reinsurance programme and protect the group from frequency of major catastrophe losses,' Amlin Chief Executive Charles Philipps said in a statement.
The bond sale marks the first time Amlin has turned to the catastrophe bond market.
Catastrophe bonds were developed in the 1990s to help insurers and reinsurers manage their exposure to natural disasters by transferring some of the risk to capital market investors.
Buyers of catastrophe bonds receive interest payments that are largely insulated from wider macroeconomic or financial market developments, but risk losing all or some of their money if a natural disaster occurs.
Several recent catastrophe bond issues have been increased after investor demand exceeded the original target size.
There is pent-up demand for the securities after leading risk-modelling agency RMS in February said the risk of hurricane damage to inland U.S. areas was greater than first thought, raising loss estimates on some bonds, and choking off new issuance.
Insurers are on course to absorb $108bn in catastrophe losses in 2011, making it the industry's second-costliest year for natural disasters on record after 2005, when Hurricane Katrina devastated the city of New Orleans