Aspen Insurance Holdings’ first-quarter net income fell by more than half to $US30.8 million ($41 million) after catastrophe losses from weather events in the US and UK.

The insurance arm had pre-tax catastrophe losses, net of reinsurance recoveries, of $US9.4 million ($12.5 million), and the reinsurance division had $US14.8 million ($19.7 million).

Overall gross written premium (GWP) grew 11.9% to $US1.16 billion ($1.54 billion), marking the first time GWP has passed the billion-dollar mark.

“Our strong results include GWP growth across both Aspen Re and Aspen Insurance as a result of our targeted growth strategy,” CEO Chris O’Kane said.

“Both segments generated underwriting profits, we improved our total expense ratio and we continue to implement our operational effectiveness and efficiency program.”

Net written premium fell to $US635.5 million ($845.7 million) from $US686.2 million ($913.18 million) in the corresponding period last year, and the combined operating ratio worsened to 97.8% from 97%.

Net investment income fell to $US47.3 million ($62.95 million) from $US47.7 million ($63.49 million).