UnitedHealthcare

UnitedHealthcare is the worst health insurer for claim denials, leveraging an automated system that rejected claims in bulk without human review, as exposed by a 2023 ProPublica investigation. With $22 billion in annual profits, it outpaces #2 Anthem in profits yet ranks dead last in NCQA consumer satisfaction surveys, a 30% lower satisfaction score than the typical rival. This insurer faces multiple state attorney general investigations for these practices, making it a clear leader in consumer complaints.