Investor Ron Conway and Zillow CEO Rich Barton are among 13 new billionaires who have agreed to give away most of their fortunes by signing the Giving Pledge

• Famed Silicon Valley investor Ron Conway, Zillow cofounder Rich Barton, and early Facebook employee Jeff Rothschild are among this year's new signatories of the Giving Pledge, thereby agreeing to give the majority of their net worths to charity.
• This year's 13 additions to the Giving Pledge have a combined net worth of around $40 billion.
• The Giving Pledge was founded in 2010 by Bill and Melinda Gates and investor Warren Buffet and has since garnered the signatures of over 200 billionaires, including Facebook CEO Mark Zuckerberg and Salesforce CEO Marc Benioff.
• Still missing from the pledge's signatories is Amazon CEO Jeff Bezos, who is the richest person in the world with a net worth of more than $200 billion.
• Bezos has been criticized for not donating enough to charity and is the only American among the five richest people in the world who hasn't signed the Giving Pledge.

A new round of billionaires has signed onto Bill Gates and Warren Buffett's Giving Pledge, whose signatories agree to give the majority of their fortunes away.

The new billionaires include Zillow cofounder and CEO Rich Barton as well as famed Silicon Valley "super angel" investor Ron Conway, according to the Giving Pledge's website. Early Facebook employee Jeff Rothschild, who has a net worth of $3.8 billion according to Forbes, and Blackstone CEO Stephen Schwartzman also signed this year. As Forbes estimates, the combined net worth of the new signatories sits at more than $40 billion.

The Giving Pledge was founded in 2010 by Bill and Melinda Gates and investor Warren Buffet as a "movement of philanthropists who commit to giving the majority of their wealth to philanthropy or charitable causes, either during their lifetimes or in their wills." Signatories must be bona fide billionaires.

It has since garnered the signatures of over 200 billionaires across the world, like Microsoft co-founder Paul Allen, Facebook CEO Mark Zuckerberg, and Salesforce CEO Marc Benioff.

But a 2020 report from the think tank Institute for Policy Studies found that the majority of the original signatories are now much richer than they were when they signed back in 2010, suggesting that they are making money faster than they are giving it away.

As Forbes notes, the pledge isn't binding, meaning Giving Pledge can't force those who sign to give their fortunes to charitable organizations. The Giving Pledge also doesn't oversee donations made by signatories.

Read more: Jeff Bezos is the first person ever to be worth $200 billion. This is how the Amazon CEO's immense wealth stacks up to the average US worker, the British monarchy, and entire countries' GDP.

Some billionaires have been criticized for not donating enough to charity organizations - Amazon CEO Jeff Bezos has accumulated a net worth of more than $200 billion since first becoming a billionaire in 1997. He is the richest person in the world and the only American in the world's five richest that has not signed the Giving Pledge.

Bezos' ex-wife, Mackenzie Scott, signed the Giving Pledge in mid-2019 after her $38 billion divorce settlement. She has donated more than $4 billion over the last few months to more than 300 organizations to help people hit hard by pandemic-driven economic trouble.