Commercial automobile insurance could be the leader in terms of net written premium growth in commercial lines this year, according to a study from A.M. Best Co. Inc.

In fact, commercial auto was one of only four commercial property/casualty lines that experienced year-over-year net written premium growth during the first quarter of this year, said Oldwick, New Jersey-based Best in “Resurgent Catastrophe Losses and Declining Investment Income Impact U.S. P/C First Quarter Results.”

Overall, U.S. property/casualty insurers' commercial net written premium dropped an average of 2.8% during the first quarter of 2016, according to the study released the week of July 4-8.

Allied lines, including earthquake, inland marine, commercial automobile liability and commercial auto physical damage, also posted gains in net written premium, the study found.

Best said it expects commercial auto to be the “standout” in terms of commercial lines net written premium growth this year, “reflecting rate increases taken as the line demonstrated increased accident frequency and severity in recent years. In what may be a sign of good news, companies reported a decline in the commercial auto liability loss ratio in 2016 compared to 2015 based on our Quarterly Underwriting Survey.”

Best cautioned, however, that “any relief the decline in liability losses offers is tempered by an increase in the loss ratio on physical damage, for both commercial and private passenger lines.”

Best said the increase in auto physical damage losses “may relate to the increase in catastrophe claims in the quarter, with the industry posting its highest first-quarter catastrophe losses since 2011.”

Best said that catastrophe losses for the first quarter of 2016 reached $5.1 billion, based on A.M. Best's Quarterly Underwriting Survey. Among the events driving losses in the quarter were a series of severe storms that affected nearly all parts of the country in March, a significant winter storm in February, and flooding and extreme weather in California in January, according to Best.

“This is the highest reported first-quarter catastrophe loss since 2011's $6.4 billion — which included not just U.S. storm losses, but losses from two major international events: the Christchurch, New Zealand, earthquake and the Tohoku earthquake and tsunami in Japan.”

Those losses took their toll on property/casualty insurers' net income during the first quarter of 2016, which dropped 24% from that of the corresponding period in 2015 to $18.0 billion. The report found that industry posted an underwriting gain of $2.1 billion for the quarter, down 46.2% from that of first quarter 2015.

The industry's combined ratio deteriorated to 97.4% from 95.8%.

Net investment income and realized gains also declined 4.2% to $11.1 billion while realized capital gains dropped 47.5% to $2.5 billion.