13. Steve Ballmer — 0.32%
2018 net worth: $38.4 billion
Amount donated: $121 million
How he made his billions: Ballmer is a former CEO at Microsoft who joined the company early on as its 30th employee.
Donations made: Ballmer and his wife run the Ballmer Group, a charity that focuses on "efforts to improve economic mobility for children and families in the United States who are disproportionately likely to remain in poverty." The Ballmers' foundation has pledged millions to Harvard University, the University of Washington, and the University of Oregon.
12. Jack Ma — 0.33%
2018 net worth: $39 billion
Amount donated: $129.4 million
How he made his billions: Ma is the cofounder and executive chairman of Alibaba Group, one of the largest e-commerce companies in the world. With Ma at the helm, Alibaba had one of the biggest IPOs ever when it went public in 2014. Ma and Alibaba have invested billions in tech companies.
Donations made: When Ma announced he would be retiring from his role as Alibaba's executive chairman, he said it was so he could dedicate more time and money to his philanthropy, the Jack Ma Foundation. The charity was founded in 2014 and focuses its efforts on improving China's education system, especially in rural areas. The company pledged $45 million in 2017 to "help discover and cultivate future teaching talent in the rural regions of China."
11. Masayoshi Son — 0.53%
2018 net worth: $22.7 billion
Amount donated: $120 million
How he made his billions: Son is the founder and CEO of SoftBank, a huge Japanese investment firm that's put billions into tech startups like the We Company, Slack, and Uber.
Donations made: Son pledged about $120 million to support the victims of the 2011 Japanese earthquake and tsunami that resulted in more than 15,000 deaths. SoftBank donated an additional $12.5 million, and Son pledged to donate his annual salary to the victims until he retires. Son is also the founder and president of the Masason Foundation, which works to "support those who will create the future."
10. Laurene Powell Jobs — 0.8%
2018 net worth: $18.8 billion
Amount donated: $150 million
How she made her billions: Powell Jobs inherited billions of dollars worth of stakes in Apple and Disney from her late husband, Apple cofounder Steve Jobs, when he died in 2011. She founded a social impact firm called Emerson Collective in 2004, and bought a majority share in The Atlantic in 2017.
Donations made: Powell Jobs founded a nonprofit called College Track that helps prepare low-income students for college through tutoring and mentoring. Through Emerson Collective, Powell Jobs pledged $50 million to fund XQ: The Super School Project, an educational reform venture trying to revamp high school curricula. She also serves on the boards for nonprofits like Teach for America and Conservation International.
9. Jeff Bezos — 1.9%
2018 net worth: $112 billion
Amount donated: $2.14 billion
How he made his billions: Bezos is the founder and CEO of Amazon, the ecommerce giant that's helped him earn the title of world's wealthiest person. Bezos also runs an aerospace company called Blue Origin, and he purchased the Washington Post in 2013.
Donations made: Bezos announced in September 2018 that he was launching the Bezos Day One Fund, a $2 billion initiative to support homeless families and build "full-scholarship, Montessori-inspired preschools."
8. Larry Ellison — 2.1%
2018 net worth: $58.5 billion
Amount donated: $1.20 billion
How he made his billions: Ellison is the cofounder and chief technology officer at Oracle. He was also named to Tesla's board of directors in December 2018.
Donations made: Through the Lawrence Ellison Foundation, he's donated millions to educational and healthcare causes. Notable donations include $200 million toward a USC cancer research center, and $100 million to help eliminate polio. Ellison is one of the billionaires on this list who has signed the "Giving Pledge," which asks those who agree to promise to donate a majority of their wealth to charity either while alive or in their will.
7. Mark Zuckerberg — 2.4%
2018 net worth: $71 billion
Amount donated: $1.72 billion
How he made his billions: Zuckerberg is the cofounder and CEO of Facebook.
Donations made: Zuckerberg and his wife, Priscilla Chan, have donated more than $1 billion toward education and medical research, including a multi-million-dollar donation to a San Francisco hospital later named after Zuckerberg. The couple created the Chan Zuckerberg Initiative in 2015 to focus on "personalized learning, curing diseases, and connecting people." When they announced their organization's launch, Zuckerberg and Chan also pledged they would give away 99% of their Facebook shares to charity during their lifetimes.
Zuckerberg and Chan were some of the first to sign the "Giving Pledge" back in 2010.
6. Larry Page — 3.1%
2018 net worth: $48.8 billion
Amount donated: $1.50 billion
How he made his billions: Page cofounded Google with Sergey Brin in 1998, and now serves as CEO of Alphabet, Google's parent company.
Donations made: Page founded the Carl Victor Page Memorial Foundation, named after his father, in 2006. He's donated hundreds of thousands of Google shares to the charity. Through both the foundation and Google, Page pledged $25 million in 2014 to fight Ebola. Page also sits on the board of trustees for XPRIZE, which holds competitions to "crowdsource solutions to the world's grand challenges."
5. Ma Huateng (Pony Ma) — 4.4%
2018 net worth: $45.3 billion
Amount donated: $2.01 billion
How he made his billions: Ma is the founder and CEO of Tencent, the most valuable company in Asia. Tencent's subsidiaries include the messaging platforms WeChat and QQ, as well as several successful video game brands.
Donations made: Ma donated 100 million of his personal shares of Tencent — worth more than $2 billion — to the Ma Huateng Global Foundation to support "medical, educational, and environmental causes in China," Reuters reported.
4. Sergey Brin — 4.6%
2018 net worth: $47.5 billion
Amount donated: $2.20 billion
How he made his billions: Brin cofounded Google with Larry Page, and now serves as president of Alphabet.
Donations made: Brin has donated to charities focusing on Parkinson's research, including the Michael J. Fox Foundation. He also donated $1 million in 2009 to the Hebrew Immigrant Aid Society, a Jewish organization that helped Brin's family immigrate to the U.S. almost 40 years ago.
3. Carlos Slim — 6.0%
2018 net worth: $67.1 billion
Amount donated: $4 billion
How he made his billions: Slim and his family control America Movil, the biggest telecoms company in Latin America. Slim also owns a billion-dollar holding company in Mexico called Grupo Carso.
Donations made: Slim has donated $4 billion to his eponymous philanthropy organization, the Carlos Slim Foundation.
2. Michael Dell — 8.9%
2018 net worth: $22.7 billion
Amount donated: $2.02 billion
How he made his billions: Dell is the chairman and CEO of Dell Technologies. He also runs the investment firm MSD Capital.
Donations made: With this wife, Dell established in 1999 the Michael and Susan Dell Foundation, which focuses on children living in poverty. Dell pledged $36 million in 2016 to help rebuild Houston following extensive flooding and damage caused by Hurricane Harvey.
1. Bill Gates — 45.6%
2018 net worth: $90 billion
Amount donated: $41 billion
How he made his billions: Gates cofounded Microsoft and was once the company's largest shareholder.
Donations made: Along with his wife, Gates established the Bill & Melinda Gates Foundation, the largest private charitable foundation in the world, which has a focus on global health and poverty. The Gates family has donated more than $36 billion since the foundation launched in 2000, and Bill Gates has also donated billions-worth of Microsoft stock to the organization. The Gates family, along with Warren Buffett, launched the Giving Pledge together in 2010.