In the US pension risk transfer (PRT) market, longevity assumptions have become a decisive factor in how insurers price and win deals. WTW is extending its Geospatial Mortality Model (GMM) to the insurance market, now available to PRT writers and reinsurers pricing longevity risk.
WTW had previously offered the model to pension plan sponsors for setting longevity assumptions. It now targets the insurance market, with applications in PRT pricing, asset-liability management, and longevity risk analysis.
The US PRT market generated $51.8 billion in premium volume and a record 401 transactions in 2024, according to WTW's market data. PRT volumes will approach $100 billion annually within the next six to seven years, JP Morgan projected in a June 2025 report cited by MetLife. More than 20 active insurers now compete for group annuity business, twice as many as a decade ago, according to MetLife.
In that environment, mispriced longevity assumptions carry direct financial consequences. A carrier that underestimates how long annuitants will live takes on more liability than its pricing can support. One that overestimates risks losing bids to competitors with better data.
PRT activity accelerated sharply in the second half of 2025. New premium for single-premium PRT products rose 132% year over year to $28 billion in the fourth quarter, according to LIMRA. Buy-in structures drove much of that growth.
WTW's model draws on nearly four million life-years of mortality data, including post-COVID experience through 2024. WTW evaluated more than 200 socioeconomic factors during development. Health, wealth, and lifestyle variables emerged as the strongest predictors of longevity.
The model incorporates geospatial data alongside participant-level pension information. Where participants live, along with socioeconomic and health-related indicators tied to those locations, feeds into the mortality assumptions the model produces.
Beth Ashmore, senior managing director of retirement at WTW, said the model had already given pension plan sponsors better insight into their plans' longevity profiles. She said the firm was extending that capability to the insurance market.
Karen Grote, WTW's North American life division leader, said accurate mortality assumptions are foundational to PRT pricing and risk management for insurers. She said the model gives insurers a way to refine longevity risk management in a more competitive market.
The extension of a pension-side tool to the insurance market reflects a broader pattern in PRT. As the market has grown and more carriers have entered, the quality of underlying actuarial data has become a competitive factor. Reinsurers active in longevity risk have similarly invested in proprietary mortality research to support PRT capacity.
WTW said the model retains the geospatial methodology used in the pension market, applied now to insurer portfolios. The firm offers the tool through its Insurance Consulting and Technology division.
