Arch Capital Group’s third-quarter profit fell 41 percent to $109.3 million. The Bermuda re/insurer reported that net written premiums for the quarter grew 11.1 percent over those of the third quarter of 2012 to $839.1 million.

Total revenues grossed $861.1 million.

Net investment income dropped 9.7 percent to $66.1 million.

The combined ratio improved to 86.0 percent from 90.2 percent.

Arch said it had foreign exchange losses net of tax of $40.6 million in the quarter compared with $17.0 million during the third quarter of 2012. It said the “company has not matched a portion of its projected liabilities in foreign currencies with investments in the same currencies and may not match such amounts in future periods, which could increase the company’s exposure to foreign currency fluctuations and increase the volatility of the company’s shareholders’ equity.”

The company reported after-tax operating income available to common shareholders of $149.2 million for the 2013 third quarter, compared to $120.2 million for the 2012 third quarter.