GenStar, a provider of excess and surplus specialty property and casualty insurance, has partnered with ZestyAI, an InsurTech specialising in artificial intelligence-driven property risk analytics, to strengthen how hail, wind and severe convective storm risk is underwritten across GenStar’s commercial property portfolio.
The partnership has been formed to give GenStar more precise, property-level insight into weather-related risks, particularly for complex, multi-structure apartment and condominium properties.
By adopting ZestyAI’s Z-STORM™ model, the insurer aims to improve underwriting accuracy, align pricing more closely with risk and maintain coverage availability in markets that are increasingly exposed to severe weather events.
GenStar operates in the excess and surplus lines market, providing specialty property and casualty insurance solutions for risks that are typically more complex or harder to place in the standard market.
Its commercial property portfolio includes assets exposed to hail and wind losses, particularly in regions prone to severe convective storms. As climate-driven volatility increases, the carrier has been looking to enhance how it evaluates and manages these exposures at an individual property level.
ZestyAI develops AI-powered models that combine climatology with detailed, property-specific characteristics to predict loss frequency and severity. Its Z-STORM model is designed to support refined wind and hail peril rating, improved deductible and endorsement strategies, and earlier visibility into accumulating and emerging storm risk across an insurer’s portfolio. The technology is particularly suited to large, complex properties where traditional, broader geographic models may lack sufficient granularity.
Through the use of Z-STORM, GenStar plans to improve underwriting clarity by embedding clearer, property-level risk insights into core decision-making. The carrier also expects to expand policy availability by applying deductibles, endorsements and exclusions with greater precision, helping to keep coverage accessible in hail-prone markets. In addition, the model supports more competitive pricing for lower-risk properties while refining pricing for higher-risk exposures, and enables earlier identification of emerging storm risk to support proactive loss mitigation.
The collaboration reflects a wider trend of insurers adopting AI-driven tools to modernise property underwriting and respond to increasingly volatile weather patterns.
GenStar senior vice president, delegated division Matt Brown said, “Z-STORM gives us a more actionable view of hail risk at the individual property level. In our evaluation, the model demonstrated compelling risk-splitting lift, which allows us to further differentiate risk more effectively, price with greater precision, and ultimately strengthen relationships with our customers and distribution partners.”
ZestyAI founder and CEO Attila Toth said, “GenStar joins a growing number of carriers using AI to modernise property underwriting. With Z-STORM delivering a sharper, property-level view of hail risk across complex apartment and condo portfolios, GenStar can further strengthen underwriting and pricing decisions and identify emerging exposures earlier—before they potentially turn into avoidable losses.”
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