Why did margins compress so sharply?
The medical care ratio rose to 89.1% in 2025 from 85.5% in 2024, operating margin fell to 4.2% from 8.1%, and diluted EPS dropped 15% to $13.23 on revenue of $447.6 billion. Item 1A says small differences between predicted and actual medical costs produce large earnings swings because risk-based premiums are nearly 80% of revenue.