Fortune's 5 Most Influential Pharmaceutical Distributors and PBMs

Fortune has unveiled its 64th annual list of the 500 most profitable American companies, which amassed up to $12.8 trillion in revenues in the last year.

Here is a breakdown of the top five pharmacutical distributors and pharmacy benefit managers.

1. UnitedHealth Group. Ranking No. 5 on the Fortune 500 list, the nation’s largest health insurer saw revenue reach $201 billion and an overall profit of $10.56 billion in fiscal year 2017. The reason this insurer makes the list for companies in pharmaceuticals is because of its multipurpose Optum unit — which manages pharmacy benefits, provides health services and conducts data analytics. In 2017, Optum announced its intent to purchase DaVita Medical Group for $4.9 billion in cash, adding nearly 300 medical clinics to its network.

2. McKesson. Earning the No. 6 spot on the Fortune 500, this pharmaceutical distributor saw revenues of $198.5 billion and an overall profit of $5.01 billion in fiscal year 2017. Several acquisitions, including Rexall Health, as well as drug utilization rates, powered McKesson's growth in 2017.

3. CVS Health. This retail pharmacy ranks No. 7 on the Fortune 500. The company saw a profit of $6.6 billion on revenue of $184.8 billion in fiscal year 2017. CVS Health made headlines in the last year with its proposed acquisition of insurer Aetna for $69 billion — a deal that would create a healthcare behemoth with $240 billion in annual revenue. The two parties expect the deal to close in the second half of this year. It still needs approval from the U.S. Justice Department.

4. AmerisourceBergen. This pharmaceutical distributor saw revenue of $153.1 billion and a profit of $364.5 million in fiscal year 2017 earning it the No. 12 spot on the Fortune 500. AmerisourceBergen saw revenue grow in 2017 as a result of more business from some of its largest customers and strong sales of expensive cancer drugs.

5. Cardinal Health. This pharmaceutical and medical products distributor climbed one spot on this year's Fortune 500 list to No. 14. It saw a profit of $1.28 billion on revenue of $129.97 billion. Cardinal Health's revenue jumped 7 percent in 2017.