Centene Corp. withdrew its 2025 earnings guidance after an independent actuarial review showed the health insurer is likely to receive about $1.8 billion less than expected from the Affordable Care Act’s risk-adjustment program. The analysis, covering 22 of the 29 states where Centene sells marketplace plans and representing roughly 72% of its membership, indicated slower market growth and significantly higher morbidity among enrollees. Management said the shortfall would shave about $2.75 from adjusted earnings per share, compared with a previous target of at least $7.25. Investors reacted swiftly. Centene’s shares sank 40.37% to $33.78 on Wednesday, their steepest single-day drop since 2006 and the lowest close in eight years, erasing about $11 billion in market value. The sell-off spilled into the broader managed-care sector, with UnitedHealth, Humana, Elevance and Molina Healthcare falling between 3% and 22%. JPMorgan downgraded Centene to Neutral and cut its price target to $48, while UBS and Jefferies also reduced ratings or targets, warning that deteriorating risk pools could pressure industry earnings. Centene said it has begun refiling 2026 marketplace rates to reflect the higher expected morbidity and is contending with a "step-up" in Medicaid medical costs, particularly in New York and Florida. The company reiterated that its Medicare Advantage and pharmacy businesses are performing better than planned and promised further detail when it reports second-quarter results on 25 July.