Here are five things about UnitedHealth Group and its deal to buy Catamaran Corp.:

 

1. UnitedHealth currently is the second-largest Minnesota-based company based on revenue, but it will become number one after Monday’s deal. UnitedHealth had $130 billion in revenue last year, trailing only Cargill Inc., which had $135 billion in revenue in its last full fiscal year. The two companies use different reporting periods, so their results aren’t precisely comparable. With the purchase of Catamaran, which had $21 billion in revenue last year, UnitedHealth’s revenue will soar above $150 billion. That will be bigger than Target Corp., Best Buy Co. and 3M Co. combined.

 

2. The OptumRx business is the biggest inside Optum, the health services unit of UnitedHealth. OptumRx will have more than $50 billion in revenue after the deal is done. By comparison, 3M had 2014 revenue of $32 billion.

 

3. As huge as it is, UnitedHealth isn’t a household name in Minnesota because this is one of the states where it doesn’t provide health insurance to individuals and companies. The company employs about 18,000 people, mainly in Minnetonka, Eden Prairie and other offices around the Twin Cities.

 

4. Optum may someday grow to become the biggest part of UnitedHealth. The unit also provides data services to hospitals and doctors’ clinics around the country. It was hired by the federal government as well as by several states, including Minnesota, to fix troubles in websites and back-office systems for insurance exchanges that started in 2013.

 

5. Analysts generally praised UnitedHealth’s $13 billion acquisition of Catamaran, one of the biggest deals it has ever made on a valuation basis. One big risk, however, is that some of Catamaran’s insurance industry customers, who compete with UnitedHealth’s insurance unit, will leave to do business with other providers of pharmacy-benefit services. For instance, about one-third of Catamaran’s business comes from Cigna, a rival to UnitedHealth in insurance.