UnitedHealth Group shares experienced their worst daily performance since April, plunging nearly 20% in a single session as investors reacted to a series of headwinds. Trading volume spiked to approximately 66 million shares, nearly nine times the company’s three-month average daily turnover. This sell-off erased more than $55 billion in market capitalization, driving UnitedHealth’s valuation down from over $370 billion at the start of January to roughly $315 billion by the end of the trading day.

In the fourth quarter, UnitedHealth reported revenue of $113.2 billion, below consensus estimates, while adjusted earnings per share of $2.11 narrowly topped forecasts by one cent. The company’s medical care ratio climbed to 88.9%, up from 85.5% in the prior quarter, reflecting lower-than-expected Medicare Advantage rate increases—just 0.09% for 2027 versus industry projections of 4% to 6%—and elevated utilization across its covered population.

Looking ahead, UnitedHealth expects full-year 2026 revenue to decline by approximately 2% to $439 billion as it rightsizes operations and exits non-strategic markets. The company forecasts operating income in excess of $24 billion and adjusted EPS of at least $17.75, representing mid-single-digit growth. Optum is undertaking a ‘back to basics’ turnaround, streamlining provider networks and exiting low-alignment contracts, while UnitedHealthcare anticipates insuring up to 2.8 million fewer members, focusing on profitability over membership expansion.