UnitedHealth Group surprised investors with what its CEO said was an "unusual and unacceptable" quarterly earnings miss, and it lowered its outlook for the full year due to higher-than-expected medical costs,

The healthcare giant slashed its 2025 projections, citing higher-than-expected costs for people enrolled in its Medicare plans.

A surprising Medicare Advantage cost spike helped push UnitedHealth into a rare deep dive Thursday, after the health care giant chopped its 2025 forecast following a worse-than-expected first quarter.