Who says you need a college degree to be one of America’s top CEOs? Well, the law of averages does. While there are a few exceptions – like Bill Gates and Mark Zuckerberg – a formal education is standard for the top tier of the business world. The path to becoming a Fortune 500 CEO includes more than a college degree, but make no mistake, it most often includes a stop at one (or two) of the country’s colleges or universities.

However, while a bachelor's degree and a graduate degree of some kind are more than common, there is no one major or graduate degree that they all share. While business and computer science degrees are solidly represented, there are some less common inclusions. And of course, roughly half of the CEOs obtained an MBA.

Keep reading to discover the undergraduate and graduate degrees of some of the country’s top CEOs.

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Doug McMillon, President and CEO 

Company: Walmart (WMT) 

Degree(s): B.S. Business Administration from the University of Arkansas; MBA, University of Tulsa 

McMillon, a native of Jonesboro, Ark., began his career at Walmart as a summer associate at the company’s distribution center. He was also an assistant manager and a buyer trainee. Before he took the reins as CEO of Walmart, McMillon led Walmart's Sam’s Club division, and then Walmart International.

Darren Woods, Chairman and CEO 

Company: ExxonMobil (XOM)

Degree(s): B.S. Electrical Engineering, Texas A&M; MBA, Northwestern University 

Born in Wichita, Kan., Darren Woods has been a company man for ExxonMobil. Having been with the company since 1992, Woods has worked both domestically and internationally in positions for Exxon Company International, ExxonMobil Chemical Company, and ExxonMobil Refining and Supply Company. He was elected president of Exxon Mobil Corporation and a member of the board of directors in January 2016. He succeeded Rex Tillerson as chairman of the board and CEO in January 2017.

Warren Buffett, Chairman and CEO

Company: Berkshire Hathaway (BRK.A)

Degree: B.S. Business Administration, University of Nebraska; MA, Economics, Columbia University

Investing is a family trait Buffet inherited from his father, a stockbroker and U.S. congressman, in his hometown of Omaha, Neb. At the age of 11, Buffet made his first investment, and by the age of 13 he was selling horse racing tip sheets and operating a paper delivery service.

Tim Cook, CEO

Company: Apple (AAPL)

Degree: B.S. Industrial Engineering, Auburn University; MBA, Duke University

Born in Mobile, Ala., Cook’s prior stints include North American fulfillment director at IBM (IBM) and COO at Intelligent Electronics. He was also vice president of corporate materials at the Compaq Computer Corporation.

Dave Wichmann, CEO 

Company: United Healthgroup (UNH)

Degree: B.S. Accounting, Illinois State University 

Wichmann is another company man. Joining the health services and insurance company in 1988, Wichmann served as senior vice president of Corporate Development, president of United Healthcare and CFO of the company, before being named CEO in September 2017. 

John Hammergren, Chairman, President and CEO 

Company: McKesson (MCK)

Degree: B.A. Business Administration, University of Minnesota; MBA, Xavier University

Hammergren is the Chairman, President and CEO of McKesson Corporation, a company in the pharmaceutical, health information technology, and medical supplies businesses. Elected president and CEO in 2001 and chairman in 2002, Hammergren has been with McKesson since 1996, when he joined the company to lead McKesson Health Systems, focusing on healthcare institutions' pharmaceutical supply management needs. Most recently and most notably, Hammergren and McKesson have been in the news as the CEO testified along with other pharmaceutical distributors regarding the role of pharmaceutical firms in the opioid crisis. 

Larry Merlo, President and CEO

Company: CVS Health (CVS) 

Degree: B.A. Pharmacy, University of Pittsburgh, School of Pharmacy

Born and raised in the Greater Pittsburgh area, Merlo has been with CVS since the company's 1990 acquisition of Peoples Drug. Merlo made his way through the ranks at CVS before being named CEO in 2011. Directly preceding his appointment as CEO, Merlo was the President of CVS, a position he still holds. 

Jeff Bezos, Founder, Chairman, and CEO 

Company: Amazon (AMZN)

Degree: B.S. Electrical Engineering and Computer Science, Princeton University (summa cum laude)

Born in Albuquerque, N.M., Bezos and his family moved to Miami when he was a teenager. While in high school, Bezos launched his first business, the Dream Institute, which was an educational summer camp for fourth through sixth graders. Bezos also purchased The Washington Post in 2013.

Randall L. Stephenson, Chairman and CEO

Company: AT&T (T)

Degree: B.S. Accounting, University of Central Oklahoma; M.A. Accounting, University of Oklahoma

Stephenson started his career with the information technology company Southwestern Bell Telephone in 1982. He worked his way up the ranks, moving through a series of leadership positions in finance in the company, before being named chief financial officer in 2001, and then chief operating officer in 2004. In 2007, AT&T announced that Stephenson would be chairman and CEO of the company. 

Mary Barra, CEO

Company: General Motors (GM)

Degree: B.S. Electrical Engineering, Kettering University; MBA, Stanford University 

Born in Waterford, Mich., Barra’s first job at GM was as a co-op student in the Pontiac Motor Division. She has also been senior vice president and executive vice president of global product development, vice president of global human resources and vice president of global manufacturing engineering.

Larry Page, Co-Founder and CEO 

Company: Alphabet (GOOG) 

Degree: B.S. Computer Engineering, University of Michigan, Ann Arbor; M.S. Computer Science, Stanford University 

Page, who was born in East Lansing, Mich., co-founded Google, the world’s most popular search engine, as a research project while in school at Stanford. “Google” refers to the mathematical term “googol” – which is the number one followed by 100 zeros. After forming Google parent company Alphabet in October 2015 as part of a corporate restructuring, Page is now the CEO of Alphabet, while Sundar Pichai is the CEO of Google.

The Bottom Line

America’s top CEOs have degrees in a number of majors. Each leader has a strong academic background that helped them develop discipline, inventiveness and analytical skills. Those who pursued an MBA increased their business acumen while honing their management and leadership skills.