5. Health Care Service Corporation
> Revenue: $55 billion
> Number of employees: 20,975
>Headquarters: Chicago, Illinois
> Industry: Insurance

The Health Care Service Corporation is the largest policyholder-owned health insurance company and the fourth largest overall provider of health insurance in the country, according to the company. The company was founded in 1936 by a group of Chicago doctors and subsequently expanded throughout the rest of Illinois and the nation. Today, the company provides insurance for nearly 14.7 million people. It primarily operates in Illinois, Texas, Montana, New Mexico, and Oklahoma.

4. Dell Inc.
> Revenue: $55.49 billion
> Number of employees: 110,100
>Headquarters: Round Rock, Texas
> Industry: Technology & Electronics

Dell was founded by Michael Dell in 1984, when he was still in college. The company grew into one of the largest providers of computers and servers to individuals and corporations in the world. The company went public in 1988 and became one of the largest publically-traded PC makers in the world. Dell became one of the largest privately held companies in the country after Michael Dell and private equity firm Silver Lake Partners bought back the publicly traded shares in 2013. The two parties acquired the company for $24.9 billion. The company ceased public trading on October 29, 2013.

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3. State Farm Mutual Automobile Insurance Co.
> Revenue: $71.2 billion
> Number of employees: 72,000
>Headquarters: Bloomington, Illinois
> Industry: Insurance

State Farm Mutual Automobile Insurance is the nation’s largest mutual insurance company on our list by revenue. Mutual insurance companies are owned entirely by their policyholders. The company was founded in 1922 by George Jacob “G.J.” Mecherle, a retired farmer. The firm initially catered to farmers but expanded over the years into a diversified insurance provider. The company has nearly 44 million auto insurance customers, insuring more cars than any insurer in the country, according to the company.

2. Koch Industries, Inc.
> Revenue: $121 billion
> Number of employees: 102,000
>Headquarters: Wichita, Kansas
> Industry: Diversified Conglomerate

Koch Industries was founded in 1940 as Wood River Oil and Refining Company, an energy engineering business. While it has retained its energy focus, over the past 75 years the company has evolved into a diversified global conglomerate. The company employs more than 100,000 people and operates in 60 countries. The company is largely owned by members of the Koch family. It is the source of wealth behind the large-scale conservative political activities of the Koch brothers, David and Charles.

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1. Cargill Incorporated
> Revenue: $134.872 billion
> Number of employees: 143,000
>Headquarters: Wayzata, Minnesota
> Industry: Diversified Conglomerate

Cargill is the largest privately held company in the United States by revenue. Founder W.W. Cargill started the company in 1865 in the grain business. Over the last 150 years it has grown into a massive and diversified conglomerate. While the company is still heavily involved in the agriculture and food processing businesses, it also has industrial and financial services segments. The company has 143,000 employees and operates in 67 countries. It is primarily owned by descendants of the firm’s founder. Based on its 2014 revenues of $134.9 billion if the company were publicly traded it would be 11th on the Fortune 500 list, behind Valero Energy and ahead of AT&T.