Aspen posted a net loss of $184.9 million in the fourth quarter of last year — results described as “well below acceptable levels” by the insurer’s chief executive officer.

The Bermudian-based company had warned last month that underwriting losses for the quarter would be steep, and added that Stephen Postlewhite was leaving as head of Aspen’s insurance segment to be replaced by David Cohen.

However, the operating loss of $178.1 million, or $3.14 per share, was less severe than the $3.56 per share consensus forecast by Wall Street analysts.

Chris O’Kane, Aspen’s CEO, said: “Aspen’s fourth-quarter 2017 results were well below acceptable levels. While some of the losses we reported arose from abnormally high natural catastrophe activity, we recognise that despite prior actions to strengthen our insurance book, we need to take further actions to deliver substantially better results.

“We are redoubling our efforts to reduce volatility and improve Aspen’s profitability. Most of our non-natural catastrophe losses were concentrated in a limited number of lines within Aspen Insurance.

“We are actively reviewing these lines, and our focus is on taking all actions necessary to mitigate our residual exposure and deliver value to our shareholders.

“Our loss reserves are strong, and we continue to focus on achieving appropriate loss ratios and realising the benefits to our expense ratio from the successful implementation of our operational effectiveness and efficiency programme.”

For the full year 2017, Aspen posted a net loss after tax of $266.4 million or $5.22 per ordinary share, compared to net income of $203.4 million, or $2.61 per diluted ordinary share, for 2016.

Aspen wrote gross written premiums of $688.3 million in the fourth quarter, an increase of 13.6 per cent compared to a year earlier.

Pre-tax catastrophe losses totalled $137.6 million during the quarter, including $133.8 million related to wildfires in California.

Net favourable development on prior-year loss reserves was $12.6 million.

Aspen recorded $14.8 million of net realised and unrealised investment gains in the fourth quarter.

Total shareholders’ equity was $2.9 billion as at the end of last year and diluted book value per share was $40.10, down 14.2 per cent from a year earlier.

During the January 2018 renewal season, Aspen Re underwrote contracts representing $585.6 million in gross written premiums, a decrease of 0.4 per cent compared the year before. The renewal data does not include premiums related to AgriLogic.