Liberty Mutual Holding Company has reported a dramatic third-quarter turnaround, posting a $US455 million ($614.42 million) profit compared with a $US427 million ($576.61 million) loss in the corresponding period last year.

Chairman and CEO David Long says each of the group’s strategic businesses performed better than expected, with net written premium up 6%.

The combined operating ratio deteriorated 2.2 percentage points in the quarter to 97.8% due to higher catastrophe losses and unfavourable net incurred losses from previous years.

Net written premium grew 6.1% to $US9.31 billion ($12.57 billion) in the quarter.

Net investment income was $US659 million ($889.9 million), down from $US759 million ($1.02 billion) in the corresponding period last year.