Auto insurance has accounted for more of the U.S. property and casualty industry's premium volume in recent years, with several rounds of loss-fueled rate increases accelerating premium volumes in the short term, accordingly to S&P Global Market Intelligence's 2018 US Auto Insurance Market Report. Developments such as ride-sharing, the emergence of autonomous vehicle technologies and the introduction of new insurance pricing models threaten varying degrees of disruption to a sector that has historically accounted for the largest segment of overall P&C insurance premium volume.

The rate of growth on combined personal and commercial auto direct premiums written is projected to pull back to 6.4% in 2018 and even lower through the subsequent four years from the 15-year high of nearly 8% in 2017.

Tim Zawacki, Senior Insurance Research Analyst at S&P Global Market Intelligence said, "The auto insurance industry is poised to show significantly improved underwriting results after several historically challenging years. But the introduction of autonomous vehicle technology raises key longer-term questions about policy pricing and structure in a business line that has historically represented about 40% of overall property and casualty industry premium volume."

The auto insurance industry's financial results are projected to reflect the impact of corrective actions taken to address surprise spikes in the frequency and severity of claims, which had the effects of pushing losses in 2016 and 2017 to their highest levels since the start of the century.

For the personal auto business, S&P Global Market Intelligence projects growth in direct premiums written will slow to 6.3% in 2018 from 7.8% in 2017. Meanwhile, the projected 2018 growth rate for commercial auto direct premiums written is even higher at 7.3%, but it also lags the expansion of more than 8.8% that the industry achieved in 2017. The projected 2018 growth rate is well in excess of the 4.1% pace of expansion projected for the U.S. P&C industry as a whole, according to S&P Global Market Intelligence.

Additional findings from the 2018 US Auto Insurance Market Report include:

• Broad-based premium rate increases to address adverse claims trends will bring the personal auto business closer to break-even underwriting results.

• Commercial auto will pull back from the brink amid a commitment by many leading carriers to raise rates and continued macroeconomic growth.

• Consolidation of market share among the largest carriers will continue in the increasingly commoditized personal auto business.

• No dramatic shift in underwriting results over the next five years directly resulting from the way in which auto insurance is priced, underwritten and consumed.