How did UnitedHealthcare get so large? Most people probably don’t even know what UnitedHealthcare is, but don’t let that fool you. UnitedHealth Group is one of the largest companies in the United States. UnitedHealthcare’s market generally leaves it typically unnoticed among large businesses, but its annual revenue of around $228 billion makes it the sixth largest company by revenue, and its influence on the American economy is unprecedented and often looked over.