
By William Nibbelin, Head of Industry Data and Actuarial Research, Triple-I
U.S. fire and allied lines have emerged as a standout performer within the property and casualty (P/C) industry, achieving a net combined ratio of 84.8 in 2024. This marks the lines’ best underwriting performance since 2007 and the third consecutive year they have outperformed the broader P/C industry, according to Triple-I’s latest Issues Brief.
This success is particularly notable given the industry’s five-year streak of underwriting losses between 2017 and 2021. Combined ratio is the most common measure of insurer underwriting profitability. It is calculated by dividing the sum of the claim-related losses and expenses by premium. A ratio over 100 indicates the industry is paying out more than it is taking in.
What are Fire and Allied Lines?
Though often grouped together, fire and allied lines serve distinct purposes:
- Fire Insurance: Covers direct property damage caused by fire.
- Allied Lines Insurance: Acts as a broader catch-all, covering damage from other perils, such as wind, water, and vandalism.
Together, they provide property protection comparable to that of a standard homeowners’ policy or commercial multi-peril policy, but without liability coverage. The market for these lines is predominantly commercial, protecting larger risks, such as retail shops, office buildings, warehouses, large farms, and schools. Some businesses with significant large-risk exposure may carry more than one fire and allied lines policy from multiple carriers, known as “stacking.”
Shifts in Market Distribution
The way fire and allied lines policies are sold has changed dramatically over the last decade. Standard insurance policies, which once made up two-thirds of the market, dropped to just under 53 percent in 2024.
In their place, two other segments have gained ground:
- Excess and Surplus Market: This market, which handles higher-risk or non-standard properties, has grown significantly in market share, from 22 percent to over 36 percent
- Residual Market: After a period of decline, the residual market (also known as the market of last resort) has grown at an annual rate of over 12 percent since 2020.
Severe Weather Amplifies Loss Trends
Weather has increasingly dictated the performance of both lines in recent years. Allied lines insurance, which covers wind and storm damage, has experienced quarterly loss ratios greater than those of fire insurance in 17 of the past 20 quarters due to mounting severe convective storm and hurricane damage.
Though the frequency of fire and wind incidents is similar across personal and commercial lines, the severity of these losses differs. Commercial policies, which cover larger risk properties like industrial facilities and corporate high-rises, tend to have lower frequency rates but much larger severity losses when a disaster strikes. This discrepancy suggests that while fire and wind incident frequency may be predictable, the high value of commercial assets makes every major claim a significant financial event.
Healthy Competition for Consumers
Despite the challenges posed by natural disasters, the fire and allied lines market remains exceptionally competitive. In 2024, the U.S. Department of Justice classified the lines both separately and combined as “unconcentrated,” as measured by the Herfindahl-Hirschman Index (HHI), meaning there is no single dominant player stifling competition.
The number of companies writing these policies has either grown or remained flat in every state with Alabama, California, Delaware, New Jersey, and New York among the most competitive markets. This level of competition is a positive sign for the industry’s long-term stability and for business owners seeking diverse coverage options.
Learn More:
Illinois Storms Highlight Mounting Severe Weather Losses
Convective Storm Losses: Historic 3-Year Streak





