Stop-Loss at 12.7%: The Structural Break Behind the Premium

Medical stop-loss premiums for 2026 are rising 12.7% on average across Segal's 225-plan national dataset. The headline understates the problem underneath it: claimants exceeding one million dollars have grown 25% a year for four straight years.

That is a compounding frequency shift, and it has already outrun the specific attachment points self-insured sponsors negotiated in 2022 and 2023.

Key Takeaways

• 2.44 times. Compounding 25% growth over four years means a block producing four seven-figure claimants in 2022 should be producing roughly ten by 2026.
• 12.7% against 9.7% for groups holding deductibles flat, and 11.5% against 7.3% across all groups including those that raised deductibles. Carriers are repricing a widened distribution, not a one-year spike.
• $2.41 to $22.59 PMPM in allowed GLP-1 cost between 2022 and 2024, roughly 840%. That breaches an attachment point through accumulation rather than a single event.
• Above $3 million per treatment for gene and cell therapy, with some above $3.5 million, concentrated in one patient and too rare for any single group to price from its own experience.
• 65% at 120 days falling to 34% at one year. GLP-1 persistence collapses, and the accumulated spend has already entered the aggregate corridor by the time it does.

The Frequency Curve Under the Headline

Segal's SHAPE claims data warehouse shows the count of claimants exceeding $1 million growing at an average of 25% a year over the last four plan years. Compounded rather than read as a flat annual figure, 1.25 raised to the fourth power gives 2.44, so a block producing four seven-figure claimants in 2022 should be producing roughly ten by 2026. That is a threefold escalation in the event most stop-loss contracts still treat as the rare tail case, inside a horizon sponsors budget in one-year increments.

The premium comparison confirms the direction. The 12.7% average for groups holding deductible levels flat is up from 9.7% in the prior cycle, and the 11.5% increase across all groups, including those that raised deductibles or moved to aggregating specifics to blunt the number, is up from 7.3%.

The pricing mechanics matter more than the growth rate. Specific stop-loss at moderate attachment points has relied on treating claims above the deductible as a low-probability tail event, rare enough relative to a block's total claim count that a Poisson-style frequency assumption held reasonably steady between rating periods, with pooled manual rates built on trailing three-year experience absorbing the shock across the book.

A frequency process growing at a compounding 25% is not stationary within a typical pricing horizon. A rate built on trailing experience prices to the average of a period during which the true underlying frequency has already moved past that average, which is the gap between the 12.7% headline and the curve beneath it.

Two Different Ways to Breach an Attachment Point

The two cost drivers now pushing claims past specific deductibles work through opposite mechanisms, and they land in different layers of the program.

GLP-1 drugs breach through accumulation. Lockton data shows allowed per-member-per-month costs for employers covering GLP-1s for weight management rising from $2.41 to $22.59 between 2022 and 2024, roughly 840%. Segal's 2026 cost trend survey found 60% of client plans now offer anti-obesity medication coverage, contributing to a median 9% projected medical trend, the highest annual projection in more than a decade.

Individually, injectables running above $10,000 per member per year rarely breach a $150,000 or $250,000 specific deductible on their own. The exposure comes from a plan holding a growing share of its population on the drugs at once. John Thornton of Amalgamated Life put it directly: "That sustained utilization across a growing share of the covered population compounds into aggregate pressure". That is an aggregate-layer problem, which is why Segal's Q3 report tells sponsors to extend claims run-out from the standard 12/15 basis to a minimum of 12/18 or 12/24, so delayed adjudication of accumulating pharmacy claims does not fall outside the policy period.

Gene and cell therapy breaks the model from the other direction. Per-treatment costs commonly exceed $3 million, with some above $3.5 million, and they are one-time rather than recurring. A single approval can consume an entire year's specific stop-loss budget for a mid-size employer, while the underlying disease incidence is too rare for any group, even one with several thousand covered lives, to generate credible experience.

Pricing has migrated toward pooled catastrophic layers sold alongside the specific policy, with lasers applied to named individuals once a high-cost condition is identified. The smaller the group, the more that laser rests on disease-prevalence and treatment-eligibility models rather than trailing claims history.

Both drivers land on attachment points priced against a different distribution. The $150,000 to $250,000 specific attachments common in 2022 and 2023 were set against that period's claim distribution, and the effects compound rather than offset.

The probability of at least one seven-figure claim breaching the deductible has risen with the 2.44x cumulative multiplier, so the expected excess loss the carrier pays has grown faster than the deductible was designed to contain. Claims between the old attachment and roughly $1 million, where GLP-1 accumulation and mid-tier specialty spend concentrate, now retain more variance in the aggregate layer than a corridor built on 2022 and 2023 experience assumed.

A sponsor holding its specific deductible flat is self-insuring a materially larger slice of expected cost than its board approved at the last renewal, before this year's premium increase is layered on.

The Coverage Pullback Does Not Unwind the Exposure

Employers are already retreating from GLP-1 coverage, and the retreat does not reduce stop-loss exposure on the timeline the decision implies.

Among employers with 500 or more workers, 6% dropped GLP-1 coverage for 2026 and another 5% are planning to drop it or actively considering doing so for 2027. Real-world persistence explains part of the appeal: adherence falls from 65% of patients still on therapy at 120 days to just 34% at one year.

Neither movement shows up in the layer where the exposure sits. Accumulated spend from members already on therapy through much of a plan year has already flowed into that period's aggregate corridor calculation, so a plan that drops coverage or sees high attrition does not see its stop-loss exposure fall in step. Coverage decisions made in 2026 reach aggregate pricing with a lag.

Carriers are repricing on three fronts in the meantime. Lasers are applied more aggressively and to a broader set of conditions, moving past oncology and transplant history to members with documented high-cost specialty drug utilization. New exclusion language is appearing for gene and cell therapy ingredient cost, pushing that exposure toward the pooled catastrophic products built to sit alongside a standard specific policy. And aggregate-specific blending is negotiated as one joint decision rather than two line items, because a decision to raise the specific deductible mechanically increases the variance retained in the aggregate corridor, exactly where GLP-1 accumulation concentrates.

A structural fee issue sits alongside the premium story. Stop-loss interface fees currently range from $1.50 per participant per month up to $6 to $8 PPPM, and Segal is recommending sponsors push carriers toward flat monthly or quarterly fees rather than PPPM structures that scale with enrollment regardless of claims activity. On a growing block, that is a cost line rising with headcount while the claim distribution it is meant to service is moving on an entirely different curve.