Stop Loss Carriers Are the Actual Architects of Level Funded Plan Design

The standard description of a level funded plan assigns roles as follows: the employer sponsors and funds the plan, the TPA designs and administers it, and the stop loss carrier provides catastrophic reinsurance. The carrier is downstream. It prices risk that others have assembled. The plan exists first; the carrier prices it second.

This article argues the allocation runs backward. Stop loss carriers do not price risk that others have assembled. They define what is insurable at what cost, and the TPA and employer assemble plan design within that definition. Attachment points, lasers, excluded conditions, aggregate corridor specifications, and contract renewal terms establish the boundaries of what the plan can do. Everything that happens inside those boundaries, the network selection, the benefit design, the member experience, the employer’s total cost exposure, operates within the space the carrier allows. The industry describes this as the employer choosing a plan with stop loss protection. The more accurate description is the stop loss carrier deciding what kind of plan is insurable, and the employer choosing within that decision.

Attachment Points Define the Economic Structure

#

A level funded plan for a 20-person employer with a specific attachment point of $40,000 is a fundamentally different economic instrument than the same plan with a specific attachment point of $20,000. The first employer retains up to $40,000 in claims per member before stop loss activates. The second retains only $20,000. The difference in retained risk is real, material, and directly affects how the employer prices the benefit, whether the employer can absorb a catastrophic year, and what stop loss premium the employer pays for the protection.

Neither attachment point is the employer’s free choice. Both are the stop loss carrier’s underwriting decision. The carrier examines the group’s census data, age distribution, prior claims experience where available, industry SIC code, and geographic location. The carrier determines what attachment point it will offer and at what premium. The employer then selects from the options the carrier presents, each with a different premium and a different retained risk exposure. Calling this employer choice is technically accurate and substantively misleading. The employer is choosing between options the carrier designed, at prices the carrier set, subject to terms the carrier wrote.

The stop loss market priced $26.9 billion in premium in 2024 according to Allied Market Research, and the market is growing at a projected compound annual rate of 15.1 percent through 2034 driven by self-funded plan expansion. That market is not a passive price-setter responding to plan designs that TPAs and employers create. It is the underwriting infrastructure whose appetite and terms determine what level funded plans look like at the population level.

Lasers Redesign Plans at Renewal

#

The laser is where the carrier’s architectural role becomes most visible. When a stop loss carrier issues a laser on a specific member at renewal, it is announcing that one person’s expected claims exceed what the standard attachment point can absorb. The carrier will cover that member only above a higher threshold, often $100,000 or $150,000 when the plan-wide specific is $40,000. The difference between the standard attachment point and the laser threshold is risk the employer now retains for that individual.

The laser arrives as a unilateral carrier decision. The employer did not negotiate it. The employer cannot appeal it in any meaningful way. The employer’s options are to accept the laser, pay a higher premium for no-laser coverage if the carrier offers that alternative, or find another carrier who will make the same underwriting judgment and impose the same or similar laser. The member being lasered typically has no idea the adjustment has occurred. Their plan document does not change. Their network access does not change. Their out-of-pocket maximums do not change. What changes is the employer’s financial exposure for that member, silently restructured by a carrier decision the member never sees.

The plan design consequence of a laser is concrete. An employer whose project manager has Type 1 diabetes with an insulin pump and quarterly endocrinology visits, and who is being managed for early-stage retinopathy, faces a laser that may reset that member’s effective attachment point to $150,000. The employer now designs the plan knowing that this member’s first $150,000 in claims in any plan year are retained employer risk. That knowledge shapes every subsequent plan design decision: the aggregate attachment point the employer accepts, the catastrophic reserve the employer maintains, the contribution level the employer sets, the DPC or care management program the employer considers adding. The carrier’s laser has redesigned the plan.

Tokio Marine HCC’s 2025 Annual Market Report documented that large stop loss claims over $2 million have increased at an average of 26.7 percent per year since 2013. As large claim frequency rises, carrier underwriting tightens and laser usage grows. An employer renewing into a hardening stop loss market is not renewing the plan it designed. It is accepting whatever plan design the carrier’s revised underwriting permits.

Market Concentration Narrows Employer Options

#

In 2023, the top eight stop loss carriers by direct premiums written were, in order: Cigna at $5.0 billion, UnitedHealth Group at $4.4 billion, Sun Life Financial at $2.7 billion, CVS Health at $2.7 billion, Tokio Marine HCC at $2.0 billion, HCSC at $1.7 billion, Elevance Health at $1.6 billion, and Voya Financial at $1.5 billion, according to S&P Global Market Intelligence analysis. The top three carriers, Cigna, UnitedHealth, and Sun Life, together held approximately $12 billion of the $26.9 billion market, representing roughly 45 percent of total stop loss premium. In January 2025, Nationwide announced an agreement to acquire Allstate’s employer stop-loss segment for $1.25 billion, a transaction that, if approved, further concentrates the market’s larger competitive block.

Market concentration at this level has a specific consequence for small group plan design: the underwriting criteria of the leading carriers set de facto standards that the market follows. A TPA whose stop loss relationships are with three carriers is designing plans within the boundaries of what those three carriers will insure. If all three require a minimum group size of 10 lives, the TPA cannot offer a viable 7-person level funded plan. If all three require specific attachment points no lower than $25,000 for groups under 25 lives, the employer cannot structure a plan with a $15,000 specific regardless of their preference for higher retained risk and lower premium.

The consolidation trend reinforces this effect. Nationwide’s January 2025 announced acquisition of Allstate’s employer stop-loss segment for $1.25 billion, pending regulatory approval, reduces the number of meaningful independent underwriting voices in the market. When a carrier acquires a book of business from a competitor, it absorbs that competitor’s client relationships and, at renewal, underwriters those clients using the acquiring carrier’s own criteria. An employer whose stop loss was placed with Allstate based on Allstate’s underwriting appetite may find at renewal that Nationwide’s criteria produce different attachment points, different laser practices, and different premium outcomes. The employer made no decision that caused this change. Carrier consolidation delivered it.

The TPA’s “plan design flexibility” is bounded by carrier appetite. TPAs that market their plan design expertise are, in practice, marketing their knowledge of what the available carriers will accept. When a small group TPA explains to an employer that a proposed benefit design is not viable, the explanation usually traces back to stop loss carrier underwriting, not to legal constraints or TPA operational limits. The carrier’s appetite is the binding constraint, and it is rarely described as such to the employer bearing the consequence.

The Reinsurance Layer Behind the Carrier

#

Stop loss carriers do not retain all the risk they underwrite. Behind the carriers sit reinsurers: Swiss Re, Munich Re, Gen Re, Employers Re, and others who provide the capital that makes stop loss underwriting viable for low-frequency, high-severity events. The reinsurance layer determines how much risk the stop loss market can absorb in aggregate. When reinsurers tighten their terms, the cascade is direct: stop loss carriers tighten their terms, attachment points rise, lasers become more common, and the employer’s plan design options narrow.

The employer operating a level funded plan in a market where reinsurance capacity has contracted is working within constraints set three layers removed from their own relationship: the reinsurer constrains the stop loss carrier, the stop loss carrier constrains the TPA, the TPA presents the employer with what remains. At no point in this cascade does the employer have visibility into what is driving the constraint. The TPA explains that the renewal terms are tighter than last year. The broker confirms that market conditions are difficult. The employer accepts a higher attachment point or a new laser and attributes the change to the healthcare cost environment. The actual mechanism, reinsurance market tightening transmitted through the carrier layer, is invisible.

No disclosure obligation currently requires stop loss carriers to communicate to employers the reinsurance conditions that drive their underwriting decisions. The carrier’s renewal letter describes the new attachment point and the new premium. It does not disclose that reinsurers increased their per-occurrence retention requirements, that treaty terms tightened because global catastrophic loss experience consumed reinsurance capacity in other lines, or that the carrier’s own treaty is up for renewal under conditions more restrictive than the prior year. The employer who wants to understand why their plan costs more and covers less at renewal has no pathway to that information through the current market structure.

Voya Financial’s 2024 stop loss results illustrate the cascade in both directions. After reporting a higher-than-expected loss ratio for medical stop loss in its third-quarter earnings, Voya announced that its stop loss premiums would increase at twice the 2024 rate in 2025. Cigna simultaneously announced corrective actions after stop loss claims impaired its fourth-quarter 2024 earnings. Both announcements triggered equity market reactions: Voya’s stock fell 11.1 percent and Cigna fell 11 percent in a single week in December 2024. The financial markets understood immediately that carrier-level stop loss results would transmit directly and inevitably to employer-level plan costs at renewal. The employers whose plans were affected by those concurrent correction cycles received the impact as higher renewal premiums and tighter attachment terms, with no awareness that both carrier profitability and global reinsurance economics were the upstream cause.

The Fiduciary Dimension

#

The employer’s status as ERISA plan sponsor creates a fiduciary obligation to administer the plan prudently and solely in the interest of plan participants. Among the most important fiduciary decisions an employer makes is the selection and monitoring of the stop loss carrier. If the stop loss carrier is the actual architect of plan design, then the employer’s fiduciary act of selecting and monitoring the carrier has consequences that most small employers do not understand they are accepting.

When an employer selects a stop loss carrier based on broker recommendation and annual premium, the employer is, effectively, selecting a plan architect. The carrier’s underwriting philosophy, its laser practices, its renewal behavior, its aggregate corridor requirements, and its claims management approach will determine what the plan can do for the next policy year and in which direction it will be adjusted at the following renewal. An employer who changes stop loss carriers at renewal is not just changing a vendor. The employer is changing architects mid-construction and accepting whatever plan the new architect will insure.

Most small employers do not evaluate stop loss carrier behavior at this level of specificity. The broker presents two or three quotes with premium differences and attachment point comparisons. The employer selects the option with the best apparent value. The underwriting philosophy, the carrier’s historical laser rate, the carrier’s run-out claims payment practices, and the reinsurance structure behind the carrier are not in the comparison. The employer’s fiduciary duty to prudently select service providers technically requires evaluation of these factors. The market structure makes that evaluation nearly impossible for an employer without specialized stop loss advisory expertise, and most brokers in the small group market do not provide it at that depth.

The Honest Account of Who Designs the Plan

#

The employer’s plan design authority is real within its boundaries. The employer can choose among the benefit designs the carrier will insure, select the network the TPA offers, set the contribution level for employee premiums, and decide whether to add supplemental programs like direct primary care or pharmacy carve-outs. These are genuine decisions with genuine consequences.

The carrier’s architectural authority operates at a higher level: it establishes the cost and risk boundaries within which all of those employer decisions occur. An employer who wants to offer a $10,000 specific attachment point to retain more risk and capture a lower stop loss premium will find that no carrier in the small group market will underwrite it. An employer who wants to insure a member whose expected annual claims are $250,000 above the standard attachment point will find that the carrier will laser that member or exclude them from stop loss coverage entirely. The employer’s plan design authority stops where the carrier’s underwriting appetite begins.

This matters beyond semantics. If the carrier is the plan architect, the employer’s oversight obligation extends to carrier behavior, not just TPA administration. Carrier practices that systematically use lasers to exclude predictable high-cost members transfer risk back to employers without adequate disclosure. Carrier contract terms that allow premium increases of 20 to 30 percent at renewal on short notice restructure the employer’s financial exposure without meaningful ability to react. Reinsurance-driven market contractions that tighten available plan design options for all employers simultaneously are external forces that shape the employer’s benefits program as surely as any decision the employer makes directly.

The insurance industry describes stop loss as protection the employer purchases. A more precise description: the stop loss carrier defines what kind of plan the employer is permitted to operate, prices that permission annually, and reserves the right to change the terms of the permission at each renewal. Calling the employer the plan architect and the carrier the risk pricer is a legal convention that accurately describes the contract structure and inaccurately describes operational reality. The stop loss carrier is the plan architect. The employer is the client who selects from the architect’s available designs, within the architect’s terms, at the architect’s price.