The pledge, launched by Bill Gates and Warren Buffett in 2010, is a campaign that encourages billionaires from across industries to commit to giving away at least half of their fortunes to charity during their lifetimes.
Notably, it's a nonbinding commitment: Its founders describe it as a "moral commitment," and critics argue that its loose rules lack enforcement. So far, it's been signed by 236 billionaires, including Gates and Buffett, as well as Elon Musk and Bezos' ex-wife, MacKenzie Scott.
But Bezos, whose recent announcement followed years of criticism over his relative lack of philanthropic giving, isn't the only billionaire who hasn't signed the pledge. It lacks the signatures of seven of the world's 11 wealthiest people, based on Bloomberg's billionaire rankings as of this week.
None of the seven responded to CNBC Make It's request for comment.
Here's who they are and what their philanthropic efforts have looked like to this point.
Bernard Arnault: $157 billion net worth
Bernard Arnault is the co-founder and CEO of luxury goods conglomerate LVMH and the world's second-wealthiest person, according to Bloomberg.
In the past, the French billionaire's net worth has approached $200 billion. He has topped Bloomberg's list of the world's wealthiest people multiple times, most recently in 2021.
Arnault has not signed the Giving Pledge, nor has he commented on the pledge publicly. There is no public record showing the extent of what Arnault has donated to charity.
However, LVMH has posted a statement online highlighting the company's philanthropic mission and noting the Arnault family's high-profile $226 million donation in 2019 to help fund repairs of Paris' iconic Notre Dame cathedral, after a devastating fire severely damaged the landmark that year.
Gautam Adani: $130 billion net worth
Gautam Adani is the chairman and founder of the Adani Group, one of India's largest industrial conglomerates. He is India's wealthiest person and the third-richest in the world, according to Bloomberg.
His net worth has nearly doubled since this time last year, as his company has made a series of acquisitions to expand into industries such as coal and transportation.
He's also ramped up his philanthropic efforts over the past year: In June, he pledged a $7.7 billion donation to his Adani Foundation, a philanthropic arm of his company that supports social causes in India such as education and health-care programs.
Jeff Bezos: $116 billion net worth
Bezos has donated more than $2.4 billion in his lifetime, according to a Forbes estimate. He has also committed to distributing a total of $10 billion through his own climate nonprofit, the Bezos Earth Fund.
But the billionaire has skirted questions about the Giving Pledge for years, especially after his ex-wife, Scott, signed it shortly after their 2019 divorce.
Scott has gone on to become one of America's most celebrated philanthropists. Bezos' critics are still waiting for him to offer more concrete details on how he intends to distribute his massive fortune to charitable causes.
Without those details, it's hard to parse how his announcement last week differs from signing the Giving Pledge, and why he made such a similar commitment without joining many of his fellow tech billionaires.
Larry Page: $88.7 billion net worth
In 2014, Google co-founder Larry Page said he didn't plan to leave all of his wealth to his two children. He didn't commit to leaving his net worth to charity, either.
Instead, the billionaire said in a TED interview that he would rather hand over the bulk of his fortune to entrepreneurs with big ideas to change the world for the better. At the time, Page named Elon Musk as one example: "He wants to go to Mars. That's a worthy goal."
In 2019, Vox reported that Page had donated over $2 billion to his own philanthropic foundation since 2004. The vast majority of those contributions ended up in donor-advised funds, which critics argue can be used as vehicles for tax breaks.
Mukesh Ambani: $88.2 billion net worth
Mukesh Ambani, the ninth-richest person in the world, is the chairman of Reliance Industries, an energy and telecommunications conglomerate and India's most valuable company.
In 2010, Ambani founded the Reliance Foundation, the philanthropic arm of his company and one of India's largest nonprofits. The foundation focuses on initiatives that provide health care and educational scholarships, as well as agricultural infrastructure in rural farming communities, according to its website.
Steve Ballmer: $86.3 billion net worth
Steve Ballmer's absence from the Giving Pledge could come as a surprise: He was one of Microsoft's earliest employees, and rose to the role of president and Gates' right-hand man before succeeding his friend as CEO in 2000. Most of Ballmer's fortune comes from his 4% stake in Microsoft.
But Ballmer has said that he and Gates have "drifted apart" since he retired from the company in 2014, which could explain why he hasn't signed the pledge that Gates co-founded.
Today, Ballmer serves as chairman of the NBA's Los Angeles Clippers, which he bought in 2014. He's also fairly active on the philanthropy front: He and his wife, Connie, run the Ballmer Group nonprofit, which has awarded over $420 million in charitable grants over the past year, according to the group's website.
Sergey Brin: $84.9 billion net worth
Like fellow Google co-founder Page, Sergey Brin has not signed the Giving Pledge. The 11th-wealthiest person in the world, Brin hasn't spoken publicly about the pledge or how much he plans to give away during his lifetime.
In the past, Brin has donated money to causes including STEM-focused educational nonprofit Girls Who Code and a reported $63 million gift earlier this year to the Michael J. Fox Foundation, which funds research into a cure for Parkinson's disease.
In 2009, Brin also donated $1 million to the Hebrew Immigrant Aid Society, an organization that helped him and his family escape the Soviet Union and migrate to the U.S. when he was a child.
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