NEW YORK >> MacKenzie Bezos, who finalized her divorce from Amazon founder and CEO Jeff Bezos earlier this year, is pledging to give away half her fortune to charity.

The novelist said today that she signed The Giving Pledge, a campaign to get the ultra-wealthy to pledge at least half their fortune to charitable causes. It was created in 2010 by billionaire investor Warren Buffett and Microsoft co-founder Bill Gates and his wife Melinda Gates.

Those who join can give away their money while they are alive or give instructions in their wills. They also decide where and how their money is donated.

In a letter today, MacKenzie Bezos did not say how she plans to give her money away. The divorce leaves her with a 4% stake currently worth more than $36 billion in the online shopping giant.

“I have a disproportionate amount of money to share,” she said in her letter.

Jeff Bezos, who hasn’t signed The Giving Pledge, tweeted his support: “MacKenzie is going to be amazing and thoughtful and effective at philanthropy, and I’m proud of her. Her letter is so beautiful. Go get ‘em MacKenzie.”

The Bezoses, who have four children, first announced they were divorcing in January ahead of a National Enquirer story that revealed Jeff Bezos was having an affair with a former TV host. He later accused the tabloid’s publisher of threatening to publish explicit photos he sent to his lover unless he stopped investigating how the Enquirer obtained the private messages. The National Enquirer has denied the accusation.

Jeff Bezos, who founded Amazon as an online bookstore more than two decades ago, has become the world’s richest man thanks to Amazon’s surging stock price. His stake in the company after the divorce is worth more than $108 billion.

He has wrestled with how to give away some of his fortune, asking his Twitter followers in 2017 for philanthropic ideas. Last year, he committed $2 billion to a charitable fund that will focus on opening preschools in low-income neighborhoods and donate money to nonprofits that helps homeless families. So far, he has given $100 million to that fund. In the past, he has also said that he sees his self-funded space exploration company Blue Origin and his purchase of The Washington Post newspaper as “contributing to society and civilization.”

The Giving Pledge said, today, that MacKenzie Bezos was one of 19 new people or couples who joined the pledge, bringing the total number to 204. Others who have signed the pledge include Elon Musk, co-founder of electric car company Tesla, and oil baron T. Boone Pickens.