MacKenzie Bezos pledges to give away half her $37B fortune to charity

MacKenzie Bezos has pledged to give away half of her $37-billion US fortune to charitable causes, signing on to a philanthropic initiative championed by several other high-profile billionaires.

The ex-wife of Jeff Bezos, founder and CEO of Seattle-based Amazon, finalized her divorce in April and reportedly got a stake in the online shopping giant worth over $35 billion. That makes her the third richest woman in the world, behind Walmart heir Alice Walton and Jacqueline Badger Mars, heir to the Mars candy fortune.

"Tremendous value comes when people act quickly on the impulse to give," Bezos said in a letter posted on the website of The Giving Pledge, an initiative started in 2010 by 40 of the wealthiest people in the U.S.

It involves billionaires pledging at least half of their wealth to charitable causes either while they are alive or in their wills. The two leaders are Bill Gates and Warren Buffett, but many more have since joined. "No drive has more positive ripple effects than the desire to be of service," Bezos's letter reads.

MacKenzie Bezos's name was added to the list of official signatories on over the weekend, along with 18 other people. Other prominent individuals who had already signed include:

• Mark Zuckerberg, Facebook founder.
• Carl Icahn, an investor.
• Larry Ellison, Oracle founder.
• Elon Musk, Tesla CEO.
• Ted Turner, media mogul.
• Jeff Skoll, eBay founder. 

So far, about 200 individuals or families have signed on to the pledge, with a notable exception of Jeff Bezos, who individually remains the richest man in the world, even after his divorce. According to the latest calculations by Bloomberg, his net worth Tuesday was roughly $113 billion. It increased by almost $500 million on Monday alone.

"We each come by the gifts we have to offer by an infinite series of influences and lucky breaks we can never fully understand," said Bezos, a novelist and founder of an anti-bullying organization, in her letter. "In addition to whatever assets life has nurtured in me, I have a disproportionate amount of money to share."

A history of charitable giving

Her philanthropic history offers a hint of the types of charitable initiatives she may support. According to The Giving Pledge, she is a backer of marriage equality and has previously donated to a group called Washington United for Marriage, which is in the U.S. state where she lives.

"She has also supported transitional housing for homeless families through the Day 1 Families Fund, college scholarships for undocumented immigrants brought to the United States as minors through TheDream.US, and efforts to reduce political polarization through With Honor, a non-partisan organization working to increase the number of veterans in political office," the group said.

"She has funded cancer research through donations to the Fred Hutchinson Cancer Research Centre, and Alzheimer's research through the Diagnostics Accelerator at the Alzheimer's Drug Discovery Foundation. In 2013, she founded Bystander Revolution, an anti-bullying organization, where she serves as executive director."

While her ex-husband Jeff has not been compelled to make a similar pledge himself, he did offer words of encouragement to his ex-wife in a tweet on Tuesday.