The US annuity market has doubled in five years. Sales reached a record $464 billion in 2025, indexed products now account for nearly half of them, and private capital has moved from the edge of the industry to its centre, with investor owned insurers writing roughly a third of new fixed annuity business. Behind that growth sits a simple machine: guaranteed liabilities funding credit portfolios at 10 to 1 leverage, on margins measured in basis points.
This paper explains how that machine works, from the liability side first. It walks through the products and their behaviour, the spread arithmetic and the capital that governs it, the five ownership structures now running the model, the regulatory repricing under way since 2023, and the sequence by which the model fails when it fails. It closes with a practical standard: five structural criteria and fifteen diligence questions, all answerable from documents rather than assurances, applicable to any platform in the market.
