Bermuda-based Axis Capital Holdings Ltd. and Arch Capital Group Ltd. have reported third-quarter earnings more than double those of the prior-year period, owing in part to and foreign exchange gains.

Axis on Wednesday reported third-quarter net income of $279.1 million, more than double the $137.1 million in the prior-year period, owing in part to lower catastrophe losses and foreign exchange gains, the Pembroke, Bermuda-based insurer and reinsurer said.

Third-quarter net written premiums fell 4.1% from those of the same period a year earlier to $687.2 million. Third-quarter investment income also dropped 35.6% to $66.6 million. Foreign exchange gains, however, rose to $72.3 million from a loss of $56.9 million in the prior-year period, and net realized investment gains reached $77.4 million from a $4.7 million loss in 2013.

Axis estimated natural catastrophe and weather-related pretax net losses of $22 million, primarily related to weather events in North America, compared with $51 million net of reinstatement premiums incurred during the third quarter of 2013. The combined ratio, however, deteriorated to 92.2% from 86.3% during the same period in 2013.

For the first nine months of the year, Axis posted net income of $607.0 million, an 18.5% increase over that of the same period in 2013. Net written premiums increased 2.1% to $3.35 billion. Investment income dropped 10.6% to 264.2 million. The combined ratio deteriorated slightly to 91.6% from 90.5% during the first nine months of 2013.

“We delivered strong underwriting results reflecting low catastrophe losses in the quarter, ongoing favorable reserve development and the value of our diversification, as well as the benefits of a more holistic approach to risk management,” Axis President and CEO Albert Benchimol said in a statement.

Meanwhile, Arch also reported Wednesday that third-quarter net income had more than doubled to $223.2 million from $109.3 million during the same period a year earlier, driven in part of foreign exchange gains.

Net written premiums increased 2.5% to $859.7 million and investment income increased 9.2% to $72.2 million. The combined ratio deteriorated to 88.5% from 86.1%.

Foreign exchange gains played a key role in the company’s performance.

“On a pretax basis, net foreign exchange gains for the 2014 third quarter were $56.0 million, compared to net foreign exchange losses for the 2013 third quarter of $40.6 million,” the company said in its earnings release. “For both periods, such amounts were primarily unrealized and resulted from the effects of revaluing the company’s net insurance liabilities required to be settled in foreign currencies at each balance sheet date.”

For the first nine months of 2014, Arch’s net income rose 13.3% to $602.7 million. Net written premiums rose 8.1% to $2.81 billion and investment income rose 5.8% to $211.7 million. The nine-month combined ratio deteriorated slightly to 86.5% in 2014 from 86.1% during the same period in 2013.