SYDNEY (Reuters)—QBE Insurance Group Ltd., Australia's biggest insurer, cut its full-year insurance profit margin target, citing record catastrophe losses in the first half for insurers worldwide and sending its shares down as much as 10%.

QBE, which has made 75 acquisitions in the last 10 years to spread to nearly 50 countries, has seen catastrophes batter its key markets of Australia, New Zealand, the United States and Japan in the first half.

While QBE in June flagged its first-half earnings would come below then-consensus estimates, investors were focusing on its full-year margin outlook with analysts expecting a cut.

QBE said it expected a full-year insurance profit margin of 11% to 14%, down from 15% to 18% expected earlier.

"The record level of catastrophes experienced by the worldwide insurance industry during the first half and the recent fall in risk-free interest rates necessitates that we lower our insurance profit range for the full year," Chief Executive Frank O'Halloran said.

Large catastrophe claims for the financial year to date came from storms and a cyclone in Australia's Queensland state, storms in the state of Victoria, other storms in Australia, New Zealand's Christchurch earthquake, the Japan earthquake and eight major tornadoes in the United States.

QBE is not alone. Global insurers including Travelers Cos. Inc., Allstate Corp. and MetLife Inc. have also warned of difficulties following an unprecedented start to the year for the industry.

First-half catastrophe claims rose to $1.08 billion, forcing QBE to take additional reinsurance cover to give it $150 million cover for large risk and catastrophe claims over $675 million.

QBE said first-half net profit was $673 million, compared with $440 million a year ago and in line with its forecast in June, which prompted analysts to cut earnings estimates.

QBE said gross written premium grew 30% in the first half to $8.9 billion and it forecast full-year growth at over 28%.

The company said it had a surplus capital of $3.3 billion, or 1.7 times over minimum regulatory requirement.