Lloyd's of London, the world's biggest insurance market, has reported a 50% fall in profits for the six months to the end of June.
Pre-tax profits came in at £628m compared with £1.32bn a year earlier.
Lord Levine, the market's chairman, described the period as the "costliest on record" following the Chilean earthquake and Gulf oil spill.
The market paid out a total of £5.9bn in claims during the six months, £365m more than a year ago.
"We have seen a higher number of catastrophes this year than we have seen for the past 20 years," Lloyd's chief executive Richard Ward told the BBC Radio 4's Today programme.
"We have not had a bad year, we have just had more claims to pay."
Mr Ward also said snow storms in the US and Europe had contributed to the high claims payout for the period.
He also confirmed that Lloyd's had not insured the Commonwealth Games as there was not enough information to price the risks involved satisfactorily.