Liberty Mutual Holdings Co. reported a $299 million net loss for the fourth quarter of 2019, compared with a $249 million profit in the same period in 2018, as the insurer grappled with liability losses form past years.

“Our response to rising loss trends in commercial lines dominated financial results in the quarter,” said David Long, chairman and CEO of Liberty Mutual on an earnings conference call Thursday.

The 2019 fourth-quarter results included $555 million in adverse development driven by liability losses compared with $40 million in favorable development during the same period a year earlier.

During the 2019 quarter, Liberty Mutual revamped its global casualty reinsurance program and bought adverse development coverage from National Indemnity Co., a unit of Berkshire Hathaway Inc., said Christopher Peirce, chief financial officer.

“This provides coverage for up to $1.3 billion in reinsurance protection for certain (global retail markets) U.S. business lines and (global risk solutions) national insurance workers compensation, commercial auto liability and general liability claims,” he said. “We paid National Indemnity a premium of $300 million … and an additional premium of $162 million.”

The actions should position Liberty Mutual for better results in the future, Mr. Long said.

“Earnings in the quarter fell below expectations but we feel the actions we took to strengthen our balance sheet and protect against further earning volatility were appropriate given the current trends. This should lead to improved core operating performance in 2020,” Mr. Long said.

Liberty Mutual’s combined ratio for the quarter was 106.7%, a deterioration of 6.3 points compared with the fourth quarter of 2018.

The insurer reported a 3.7% increase in net written premium to $9.75 billion for the quarter.

For the full year, Liberty Mutual reported a profit of $1.04 billion, a 51.7% decline compared with 2018.

Meanwhile, the company’s leadership said it was not yet greatly concerned about the impact of coronavirus, saying that the exposure for Liberty Mutual would be in cancellation insurance, some trade credit exposure and in the U.S. possibly workers comp exposure for health care workers, but that it would not be “hugely material” to its insurance operations.

“If it does arrive here, we’re prepared from a business perspective,” said Mr. Long. “Operations would be fine. Probably the most significant potential impact for us would be financial markets, and I think we’re actually pretty well-positioned” to handle those impacts.