Seventh Year of Double-Digit Growth for Expanding US Surplus Lines

According to AM Best's Market Segment Report, "Market Need for Specialized Expertise Propels US Surplus Lines Market," total US surplus lines direct premiums written (DPW) reached nearly $130 billion in 2024, a 12.3 percent year-over-year increase. This marked the seventh consecutive year of double-digit premium growth for non-admitted insurers. 

Market Dynamics and Competition 

AM Best said the market remains competitive, shaped by capital inflows, new entrants, and insurers expanding surplus lines strategies. Troubled property and casualty coverage lines and risk classes outside the appetite of standard carriers continue to present opportunities. However, pricing in some casualty risks, such as cyber liability and directors and officers coverage, has moderated, while commercial property renewals also showed signs of stabilization despite severe catastrophe activity. 

Homeowners and Climate-Related Growth 

While homeowners' insurance is a relatively small portion of the surplus lines market, AM Best noted that increased climate-related risk has fueled growth in this segment. More frequent catastrophic weather events, higher repair costs, and supply chain delays have contributed to business shifting toward surplus lines carriers. 

Shifting Market Concentration 

The report highlighted declining concentration among leading writers. The top 25 groups, along with Lloyd's syndicates, generated 65.8 percent of total surplus lines DPW in 2024, down from more than 70–80 percent historically. AM Best said this reflects the impact of new entrants, fronting companies, and private equity-backed insurers gaining market share. 

Leading Companies and Growth Trends 

Berkshire Hathaway remained the largest surplus lines group in 2024, followed by AIG and Fairfax Financial. Lloyd's syndicates accounted for 17.2 percent of total premium. Several companies, including AXIS US Operations, Kinsale Insurance, and Travelers, achieved double-digit growth, while newer entrants such as Core Specialty and MS&AD Insurance expanded rapidly. 

Financial Performance and Composite Results 

Surplus lines insurers have consistently posted stronger underwriting performance than the broader property-casualty (P&C) industry. According to AM Best, the domestic professional surplus lines composite achieved growth in underwriting profit and operating ratios in 2024, supported by careful risk selection, pricing flexibility, and customized coverage forms not subject to prior regulatory approval. 

Emerging Risks and New Coverages 

The report identified growth opportunities in emerging risk areas. AM Best pointed to surplus lines insurers' role in providing capacity for cyber coverage, addressing exposures tied to artificial intelligence, and expanding parametric solutions for catastrophe events. The market has also served as a primary insurance source for cannabis-related businesses, biotechnology, and autonomous transportation risks. 

Service Office Insights and Geographic Trends 

Midyear 2025 data from surplus lines stamping offices showed continued growth, with premiums increasing 13.2 percent year over year to $46.2 billion. Commercial liability and commercial property dominated by share, while auto liability grew by nearly 30 percent. State-level results highlighted strong growth in California, Texas, and New York, with especially high increases in Oregon, Pennsylvania, and Utah. 

Growing Role in the P&C Industry 

The share of surplus lines within US commercial property and casualty insurance continues to expand. AM Best reported that surplus lines represented 25.7 percent of commercial lines DPW in 2024, up from just over 7 percent in 2000. The segment's ability to adapt to complex risks and provide specialized coverage has cemented its role as a key part of the insurance market.

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