Berkshire's GenStar Further Sharpens Commercial Property Underwriting for Hail and Wind with ZestyAI

 General Star (GenStar), a respected provider of excess and surplus specialty property and casualty insurance and a member of the Berkshire Hathaway family of companies, has selected ZestyAI to further strengthen how it underwrites hail, wind, and severe convective storm risk across its commercial property portfolio. 

The carrier will use ZestyAI’s Z-STORM™ model to gain more precise, property-level insight for multi-structure apartment and condominium risks, further supporting underwriting, pricing, and coverage decisions.

“Z-STORM gives us a more actionable view of hail risk at the individual property level,” said Matt Brown, Senior Vice President, Delegated Division at GenStar.

“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.”

Z-STORM predicts the expected frequency and severity of severe convective storm losses by combining climatology with detailed property-specific characteristics. The model is designed to support more refined wind and hail peril rating, improved deductible and endorsement strategies, and earlier visibility into accumulating and emerging storm risk across a carrier’s portfolio.

By adopting Z-STORM, GenStar aims to further:

• Improve underwriting clarity by incorporating a clearer, property-level view of hail and wind risk into core underwriting decisions
• Expand policy availability by applying deductibles, endorsements, and exclusions more precisely—helping keep coverage available even in hail-prone markets
• Align pricing with risk, potentially offering more competitive premiums for favorable risks while refining pricing for higher-risk properties
• Identify emerging storm risk sooner, enabling proactive risk management and loss mitigation before exposures become potentially costlier for both GenStar and insureds

“GenStar joins a growing number of carriers using AI to modernize property underwriting,” said Attila Toth, Founder and CEO of ZestyAI.

“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.”