From modeling ACA risk pools across multiple enrollment cycles, the bronze-plan surge in 2026 follows a predictable pattern: when subsidies shrink, healthy enrollees downshift to cheaper plans, concentrating high-cost members in silver and gold tiers and widening the gap between premiums and actual claims. What makes the current cycle different is the compounding effect of carrier withdrawals layered on top of that metal-tier migration. Cigna, Aetna, and UnitedHealthcare are not marginal participants. Their combined departures or contractions remove millions of covered lives from competitive markets, redistribute members to remaining carriers with unknown morbidity profiles, and introduce risk-adjustment data lags that pricing actuaries cannot resolve with existing experience.

Oliver Wyman’s March 2026 framework for 2027 ACA plan development quantifies the scale of these disruptions. Enrollment dropped roughly 5% to approximately 22 million effectuated members (23.1 million plan selections per CMS), with federally facilitated marketplaces falling nearly 8% while state-based exchanges grew 2%. New consumer enrollment declined 14%, compared with a 3% decline among returning members. The variability at the state and metal-tier level is far sharper, creating pricing uncertainty that smaller modeling errors amplify through the entire rate-setting chain.

23.1M
2026 ACA Plan Selections (Down 5% YoY)
40%
Share of Enrollees in Bronze Plans (Up from 30%)
369K
Cigna Members Losing Exchange Coverage

Carrier Exit Tracker: Who Left, Who Shrunk, Who Stayed

The ACA exchange market is contracting from both directions: outright exits by national carriers and enrollment drawdowns by those that remain. Four carrier actions define the 2025–2026 contraction.

Aetna (CVS Health), effective January 1, 2026. Aetna exited ACA exchanges in 17 states, displacing approximately 1 million members. CVS Health CEO David Joyner stated during the Q1 2025 earnings call that the company saw “no near- or long-term pathway for Aetna to materially improve its position” in the individual exchange business, which was projected to lose as much as $400 million in 2025. Affected states included Arizona, California, Delaware, Florida, Georgia, Illinois, Indiana, Kansas, Maryland, Missouri, Nevada, New Jersey, North Carolina, Ohio, Texas, Utah, and Virginia (AJMC).

Cigna, effective January 1, 2027. Cigna announced on April 30 that it will sunset ACA exchange plans by year-end 2026, affecting 369,000 members across 11 states: Arizona, Colorado, Florida, Georgia, Illinois, Indiana, Mississippi, North Carolina, Tennessee, Texas, and Virginia. COO Brian Evanko framed the decision around two factors: insufficient scale to build ACA into a “meaningful operation” and a preference for redirecting resources toward Evernorth specialty and care services, pharmacy benefits, and employer coverage. Cigna’s exchange enrollment had already declined from 446,000 in Q1 2025 to 369,000, representing roughly 2% of total medical membership (Healthcare Dive; STAT).

UnitedHealthcare, enrollment reduction of approximately one-third. UHC opted for contraction rather than exit, reducing ACA marketplace enrollment by roughly one-third for 2026 and shifting its product strategy toward bronze and gold tiers. The company is prioritizing margin recovery over membership volume, directing pricing away from silver plans where adverse selection risk is most concentrated.

Centene, the largest marketplace carrier. Centene reported ACA membership falling from 5.6 million in Q1 2025 to 3.6 million in Q1 2026, a loss of 2 million marketplace members. CEO Sarah London disclosed that membership dropped from 5.5 million at year-end 2025 to 4.6 million in January and then 3.6 million in February. Despite this 36% enrollment decline, Centene posted adjusted EPS of $3.37 in Q1 2026, well above consensus expectations of $2.20 to $2.30, as rate increases and risk adjustment transfers offset the volume contraction (Healthcare Dive; Becker’s).

Carrier Action Members Affected States Effective
Aetna (CVS Health) Full exit ~1,000,000 17 Jan 2026
Cigna Full exit 369,000 11 Jan 2027
UnitedHealthcare ~33% enrollment cut ~300,000–500,000 Multiple 2026
Centene Enrollment contraction 2,000,000 decline Nationwide Q1 2026

Centene’s financial result is instructive for the repricing dynamic: the carriers that stay can achieve adequate margins in a smaller market if their rate increases accurately reflect the morbidity of the remaining population. The pricing challenge is that accuracy depends on assumptions about how many members depart, which members leave, and where those members go.

The Bronze Surge: Metal Tier Redistribution Reshapes Risk Pools

The most consequential enrollment shift for pricing actuaries is the migration from silver and gold plans to bronze. Nationally, bronze plan enrollment jumped 26%, from 7.3 million in 2025 to 9.2 million in 2026. The share of all ACA enrollees holding bronze plans rose from 30% to 40% in a single year, a 10-percentage-point compositional shift that is among the most significant plan-type changes in the marketplace’s history (healthinsurance.org; ACA Signups).

State-level data reveals even sharper patterns:

  • California: More than one-third of new enrollees selected bronze plans for 2026, up from approximately 23% in 2025. Among returning members, 23% switched from silver to bronze, compared with 6% the prior year. Silver plan selection dropped from 69% to 51% (Covered California; Oliver Wyman).
  • Maine: Bronze plan enrollment reached nearly 60% of all plan selections, a level that fundamentally changes the state’s risk pool composition (SHVS).
  • New Jersey: Silver selections fell from 83% to 72% in the first six weeks of enrollment, while bronze selections rose from 16% to 27% (SHVS).
  • Minnesota: Among active enrollees changing metal levels, 37% bought down to less generous coverage while only 9% upgraded (SHVS).
  • Maryland: More than 5,700 consumers who held gold plans switched to bronze (SHVS).

As of early January, 38% of new enrollees nationally had selected bronze plans, up from 15% two years earlier, while silver fell from 53% to 35% and gold dropped from 31% to 25% (NBC News).

This migration creates two overlapping pricing problems. First, bronze plans have lower actuarial values (approximately 60% versus 70% for silver), meaning enrollees bear higher out-of-pocket costs. The consumers choosing bronze are disproportionately younger and healthier: they are making a revealed-preference statement that their expected claims are low enough to tolerate higher deductibles. Second, as healthy members leave silver and gold tiers, the remaining population in those tiers skews sicker, pushing per-member-per-month costs above the rates that were filed based on a broader enrollment mix. Risk adjustment transfers between metal tiers within a carrier’s book partially offset this, but transfers calibrated to the prior year’s enrollment composition will systematically undershoot when the composition shifts this rapidly.

Geographic Redistribution: Texas Gains While the Southeast Contracts

The enrollment decline is geographically uneven. Federally facilitated marketplace states (HealthCare.gov) experienced an 8% enrollment drop, while state-based exchanges grew 2%. Within the federal platform, state-level divergence is stark.

Texas posted a net gain of approximately 206,000 plan selections year over year, reaching 4.2 million enrollees and representing the largest numerical gain in the country. Texas bucked the national trend despite rising premiums, suggesting that the state’s large uninsured population and lack of Medicaid expansion continue to drive demand for marketplace coverage (Texas 2036; CMS).

By contrast, Florida lost approximately 197,000 exchange plan selections. Georgia experienced a 14.3% decline. North Carolina posted double-digit percentage losses as well (Oliver Wyman; CMS). These southeastern states share a common pattern: large pre-2026 enrollment bases inflated by enhanced premium tax credits, significant carrier overlap with Aetna and Cigna exit markets, and non-expansion Medicaid programs that limit alternatives for displaced members.

For pricing actuaries, geographic redistribution matters because the ACA’s risk adjustment operates within states, not across them. A carrier picking up displaced Aetna members in Florida faces a different morbidity profile than one absorbing Cigna members in Texas, yet both must set 2027 rates with limited data on the health status of incoming enrollees. Oliver Wyman specifically identifies the “returning members with unknown morbidity and lagged risk-adjustment data” as a core 2027 pricing risk.

Risk Pool Repricing Mechanics: Where Small Errors Compound

The convergence of carrier exits, metal-tier migration, and geographic redistribution creates a repricing environment where small modeling errors carry outsized consequences. Oliver Wyman’s framework identifies this as the defining characteristic of the 2027 planning cycle: in a redistribution-driven market, the traditional approach of trend-adjusting last year’s experience breaks down because the population generating next year’s claims is compositionally different from the population that generated last year’s data.

Three specific mechanisms amplify pricing uncertainty:

Lagged risk-adjustment data. The ACA risk adjustment transfer formula calculates payments and charges based on plan-level risk scores relative to the statewide average. Risk scores are derived from diagnosis codes in claims data, which lags enrollment by 12 to 18 months. When a carrier exits and its members redistribute across remaining plans, the receiving carriers absorb members whose risk scores reflect the prior carrier’s coding practices and network utilization patterns. A member coded at a 1.2 risk score under Aetna’s provider network may generate claims corresponding to a 1.4 risk score under a different network with different referral patterns and clinical documentation standards. This coding migration effect is invisible in the first year and only partially correctable in subsequent years (American Academy of Actuaries).

Statewide average risk score recalibration. As the overall pool shrinks and average acuity rises, the statewide average risk score increases. Plans that previously received risk adjustment transfer payments may see those payments decline if the statewide average moves closer to their own risk profile. Conversely, plans that retained relatively healthy books face larger transfer charges. The net effect is a recalibration that redistributes costs across remaining plans without injecting new money into the market. Actuaries filing 2027 rates must project not only their own plan’s enrollment composition but also the statewide average risk score, which depends on every other carrier’s assumptions about the same adverse selection dynamics.

Bronze plan cost-sharing interaction. Bronze plans have higher deductibles and lower actuarial values, which suppress claims utilization through cost-sharing. A healthy enrollee who moves from silver to bronze may generate 15–25% lower claims not because their health status changed but because their cost-sharing exposure increased. When pricing actuaries use prior silver experience to project bronze claims, they must apply an induced-demand adjustment that is itself uncertain. The ACA risk adjustment model includes an actuarial value factor to account for induced demand differences across metal tiers, but the calibration was developed under a different enrollment distribution. With bronze enrollment jumping 10 points in a single year, the historical calibration may understate the actual induced-demand effect at the new metal-tier mix.

Oliver Wyman’s Five Strategic Imperatives for 2027

Oliver Wyman’s March 2026 framework prescribes five imperatives for carriers navigating the 2027 planning cycle. Each addresses a specific dimension of the repricing challenge.

1. Stress-test granular economics at FPL-cohort level. Rather than pricing at the state or rating-area level, carriers should decompose their books by federal poverty level cohort, geography, and metal tier to identify where enrollment shifts create pocket-level margin erosion. A carrier that appears adequately priced statewide may face losses concentrated in a handful of rating areas where displaced members from exiting carriers skew the local risk pool. Oliver Wyman specifically recommends stress-testing at the intersection of FPL cohort and metal tier, where the subsidy-driven enrollment changes hit hardest.

2. Deploy selective pricing aligned to utilization management capability. Not all carriers have equivalent network management, prior authorization infrastructure, or pharmacy benefit design to manage the morbidity of a post-exit risk pool. Oliver Wyman advises carriers to price selectively in markets where their utilization management capabilities match the expected claims profile, rather than competing broadly on premium in markets where their cost structure cannot absorb the incoming morbidity. This is a structural argument against geographic expansion in a contracting market.

3. Strengthen risk-adjustment rigor immediately. With lagged data and coding migration effects, carriers that invest in prospective risk-score documentation, provider engagement for hierarchical condition category (HCC) capture, and real-time claims monitoring will gain a competitive advantage in risk-adjustment accuracy. Oliver Wyman frames this as a revenue-cycle function, not a compliance function: the difference between a risk score of 1.15 and 1.25 on a $6,000 per-member-per-month premium translates directly to transfer payment magnitude.

4. Prototype non-standard plans and broader coverage options. The proposed 2027 NBPP opens the door to plan designs that do not exist in the current market. Carriers that prototype non-network plans, multi-year catastrophic products, or value-based insurance designs during the 2027 filing window will be positioned to capture enrollment segments that current metal-tier structures cannot reach. Oliver Wyman cautions that prototyping requires actuarial resources to price products with zero credible experience data, echoing the credibility challenges documented in the 2026 filing cycle.

5. Adopt multi-year portfolio management discipline. Rather than filing rates for 2027 in isolation, carriers should build 2027 filings as the first year of a multi-year pricing trajectory that assumes ongoing enrollment contraction, continued bronze migration, and incremental regulatory changes. Single-year rate adequacy creates the death-spiral dynamic where aggressive pricing in one year forces over-correction the next. Oliver Wyman recommends a three-year horizon that absorbs annual volatility within a portfolio-level return target.

The 2027 Rule Changes: Structural Unknowns Layered on Pricing Uncertainty

The HHS Notice of Benefit and Payment Parameters for 2027, proposed in February 2026, introduces plan design changes that interact with the carrier exit dynamics in ways that pricing actuaries cannot yet quantify.

Non-network plans. CMS proposes allowing plans without contracted provider networks to be certified as qualified health plans. These plans would set benefit payment amounts and require issuers to demonstrate that sufficient providers, including Essential Community Providers and mental health providers, are willing to accept those amounts as payment in full. From a pricing perspective, non-network plans introduce out-of-network utilization patterns that are fundamentally different from managed-care claims experience. Actuaries filing rates for non-network products will have no credible experience data and must rely on professional judgment calibrated against reference-based pricing analogs from the employer market (Health Affairs; Georgetown CHIR).

Multi-year catastrophic plans. The proposed rule would permit catastrophic plans with terms of up to 10 years and deductibles potentially exceeding $10,000 for individuals and $21,000 for families. These products, which could incorporate value-based insurance design incentivizing health-promoting activities, would expand coverage options for price-sensitive consumers who currently select bronze or forgo coverage entirely. The actuarial challenge is pricing a 10-year guaranteed product in a market where medical trend, enrollment composition, and regulatory rules change annually. Multi-year rate guarantees in the individual market have no ACA-era precedent (CMS NBPP Proposed Rule).

Adult dental benefit removal. The proposed rule would prohibit states from including routine non-pediatric dental services as an Essential Health Benefit. States that had updated their EHB-benchmark plans to include adult dental would lose that option. For carriers in affected states, removing dental from the EHB reduces the minimum actuarial value floor and potentially shifts dental utilization to supplemental or voluntary products. The pricing impact depends on the proportion of current premium attributable to adult dental and whether removed benefits reduce adverse selection by lowering premiums enough to retain marginal enrollees (ASCO; Georgetown CHIR).

The Academy of Actuaries Frames the Rate-Setting Challenge

The American Academy of Actuaries’ 2026 issue brief on ACA premium drivers warns that individual and small-group risk pools “are likely to deteriorate in 2026, leading to higher rates for some plans.” The Academy notes that a deteriorating risk pool increases costs for the insured population, and as costs and premiums rise, healthier individuals in particular may seek coverage elsewhere, amplifying the cycle (Actuary.org).

For the first time, the Academy’s brief includes an appendix with an illustrative timeline of the premium rate development process, highlighting how regulatory deadlines force insurers to file rates months before Congress resolves policy uncertainty. Several 2026 filings were submitted while enhanced PTC extension legislation was still under deliberation, requiring dual-scenario actuarial assumptions. This timing mismatch between political decision-making and actuarial rate-setting deadlines is structural, not episodic, and it compounds the pricing challenges from carrier exits by adding a layer of policy uncertainty that cannot be resolved through better data or models.

The Commonwealth Fund provides historical context: ACA premiums grew more slowly (2.0% annually) than employer premiums (4.5%), national health expenditures (6.0%), and GDP (6.7%) between 2020 and 2025. Prior to 2026, ACA premium levels were 15% below employer market rates and 23% below small-group rates. The 21.7% average premium surge in 2026 erased years of relative affordability in a single filing cycle, driven primarily by the subsidy expiration and the adverse selection pricing it necessitated (Commonwealth Fund).

Why This Matters for Health Actuaries

The carrier exit cycle creates three dimensions of actuarial work that extend beyond the 2027 filing season.

The repricing feedback loop. If carriers that remain on exchanges set 2027 rates too low, they absorb losses from displaced members whose morbidity exceeds projections, potentially triggering additional exits. If they set rates too high, premiums accelerate the enrollment decline they were designed to price, shrinking the pool further and concentrating risk among the sickest members. Centene’s Q1 2026 result, where adjusted EPS exceeded consensus by 50% on 36% fewer members, demonstrates that adequate pricing can sustain profitability in a smaller market. The question is whether that pricing level is sustainable across multiple years as the enrollment base continues to shrink.

The risk-adjustment recalibration lag. Carriers filing 2027 rates will have partial-year 2026 data reflecting the first post-subsidy-cliff enrollment mix, but risk-adjustment parameters lag by a full benefit year. The statewide average risk scores and transfer amounts that determine plan-level economics in 2027 will be calculated from 2026 enrollment data that itself reflects a transitional year. Pricing actuaries face a recursive estimation problem: their rate filings depend on risk-adjustment assumptions that depend on other carriers’ rate filings that depend on the same uncertain enrollment projections. This circularity is inherent to the ACA risk-adjustment design, but it becomes more consequential when enrollment shifts are larger and more concentrated.

The regulatory pipeline. The 2027 NBPP proposes structural changes, including non-network plans, multi-year catastrophic products, and EHB modifications, that could reshape the competitive landscape within two to three years. Health actuaries building 2027 rate filings must simultaneously develop pricing frameworks for product categories that do not yet exist, assess competitive responses from carriers that may enter or exit specific markets, and model regulatory scenarios ranging from full NBPP implementation to partial withdrawal. Each scenario produces a different enrollment projection, risk-pool composition, and rate-adequacy assessment.

The core insight from Oliver Wyman’s framework is that the 2027 planning cycle is not primarily a medical trend problem or an adverse selection problem. It is a redistribution problem, where the movement of millions of members across carriers, metal tiers, and geographies creates pricing uncertainty that compounds through the risk-adjustment formula, the actuarial value framework, and the competitive dynamics of a contracting market. Carriers that treat 2027 as a standard trend-plus-morbidity filing will underestimate the repricing risk. Those that adopt the five-imperative framework, particularly the multi-year portfolio approach, will be better positioned to sustain exchange participation through the contraction.

Further Reading

Sources