Harvard University claimed the number one spot on a Wealth-X ranking of business schools in terms of number of billionaire alumni. Harvard’s MBA program has produced nearly three times more billionaire graduates than that of Stanford University, which emerged in second place on the list.

Wealth-X also found that 21% of world’s billionaires who have pursued tertiary-level education have an MBA. Nearly 50% of these individuals obtained their MBAs from the 10 institutions on the list.

There are 2,325 billionaires globally in 2014, according to the recently released Wealth-X and UBS Billionaire Census, and 65% of them have tertiary education.

American business schools dominate the list, taking seven of the top 10 spots. Only three institutions are based outside the United States: INSEAD in France, International Institute for Management Development in Switzerland, and London Business School in the United Kingdom.

Below is a list of the 10 business schools with the most billionaire alumni:

Some notable billionaires who have graduated with an MBA include Philip Knight, founder and chairman of sports footwear and apparel company Nike, Inc. Knight obtained his MBA from Stanford Graduate School of Business in 1962.

David Gilbert Booth graduated from Chicago University’s MBA program in 1971 and went on to establish Dimensional Fund Advisors 10 years later. An avid philanthropist, he donated $300 million to the University of Chicago’s Graduate School of Business in 2008, which was subsequently renamed University of Chicago Booth School of Business.