The 2025 Aegis Risk Medical Stop-Loss Premium Survey, published by the International Foundation of Employee Benefit Plans, reports that 49% of self-insured employers experienced at least one claimant exceeding $1 million in paid claims over the past two policy years. That is more than double the 23% reported one year earlier. The survey covers 1,268 plan sponsors representing over 1.2 million covered lives and more than $1.2 billion in annual stop-loss premium.
Cancer diagnoses now drive 92% of catastrophic claims, up from 83% the prior year, reflecting the escalating cost of immunotherapy, targeted therapy, and proton beam radiation. As survey presenter Ryan Siemers characterized it: “$3 million claims are the new $1 million claim.”
Who It Affects
Self-insured employer health plans across all size segments are exposed, but mid-market plan sponsors (200 to 2,000 employees) face the sharpest impact. A single catastrophic claimant can consume 10% to 15% of total expected claims for a mid-sized group, breaching specific deductibles and threatening aggregate corridors. Benefits directors and CFOs setting specific deductible levels, and captive health plans selecting attachment points, face the most immediate repricing pressure. Sixteen percent of employers now report $2M+ claimants, a tier that barely registered in prior surveys.
The Reserve Mechanism
The core reserve impact is a structural shift in catastrophic claim frequency: the rate at which individual claimants exceed high-dollar thresholds. When 49% of plan sponsors report a $1M+ claimant (compared to 23% the prior year), the expected number of large claims per covered life has changed at the tail. Any plan using pre-2024 catastrophic claim assumptions to project expected losses at the specific deductible level is likely understating exposure.
This frequency shift flows directly into the expected claim ratio used in Bornhuetter-Ferguson or expected-claims methods. If the ratio was calibrated to an era when fewer than one in four employers saw a million-dollar claimant, it understates the current loss pick. At the $100K specific deductible, stop-loss now costs $229.40 per employee per month, an 8.8% annual increase. At $500K, the increase reaches 10.1%, confirming that higher attachment points are absorbing leveraged severity.
The severity distribution is also widening. The 92% cancer concentration means a single therapeutic category controls the tail. Cell and gene therapies remain significant at 24% of catastrophic claims, but traditional oncology treatments, including immunotherapy and proton beam radiation, have become expensive enough to generate seven-figure claims without a gene therapy component.
What to Ask Your Actuary
- Are our expected catastrophic claim frequency assumptions still based on pre-2024 experience, and should we update them given the doubling of $1M+ claim prevalence?
- At what specific deductible level does our plan’s probability of breach exceed 50%, and has that threshold shifted since the last renewal?
- Has the cancer concentration (92% of catastrophic claims) changed our severity trend assumption for claims above the specific deductible, and do we need an explicit oncology loading factor?
What to Watch Next
The 2026 Aegis Risk survey (expected early 2027) will reveal whether the $1M+ frequency shift is structural or partly a one-year spike driven by pandemic-deferred cancer diagnoses reaching treatment. In the interim, watch for FDA cancer drug approvals in late 2026, which could push the average catastrophic claim cost higher. If frequency holds at or above 49% and severity continues to widen, the gap between pre-2024 loss assumptions and actual experience will compound in aggregate stop-loss corridors at renewal.