(Story updated at 12:12 p.m. ET.)
The deal is significant for UnitedHealth as it looks to grow its position as more than just a health insurance company. Optum already serves about 4 out of every 5 U.S. hospitals, providing revenue-cycle management, compliance guidance, data analytics, accountable care modeling and health information technology services. In 2013, Optum's $37 billion in revenue made up about 30% of UnitedHealth's total. The division is on pace for more than $45 billion in revenue this year.