Last verified: 9 September 2026. Climate load: model updates. Treaties: QS / XL.
Direct Answer (9 September 2026): Catastrophe modeling (also cat modelling) estimates the chance a portfolio loses more than X in a year. Four modules: hazard (event set), vulnerability (damage ratio), exposure (the book), financial (limits, deductibles, treaties). Read AAL, OEP vs AEP, PML, and TVaR. No single vendor number is “the” loss. Reinsurers validate models against their own view of risk, not by taking the vendor print as fact.
Platforms people name: Moody’s RMS, Verisk (AIR / Touchstone → Synergy), CoreLogic. Vendor pages stay on this slug.