Jeff Bezos is one of few US top billionaires who hasn't signed the Giving Pledge. Here's how much the Amazon CEO has given to charity

• $4 is the richest person in the world, with $4 $114 billion.
• Bezos' most recent - and biggest - donation was the $4 in September, but he's been $4.
• The $4 CEO is the only American among the world's five richest people who has not signed the the $4in which participants promise to give away more than half of their wealth during their lifetime or in their will.
• These are the donations Bezos is known to have made since becoming a billionaire in 1997.
• $4.

Amazon CEO Jeff Bezos may be the richest person in the world, but he isn't well-known for his billion-dollar donations and philanthropic efforts like $4 and $4.

Additional light was recently shed on Bezos' charitable donations after news that his ex-wife, MacKenzie Bezos, $4, in which participants promise to give away more than half of their wealth during their lifetime or in their will.

Among the five richest people in America, Jeff Bezos - $4 - is the only one who hasn't signed onto the philanthropic commitment.

It's not clear why Bezos has avoided joining the Giving Pledge, an initiative started by Bill Gates and Warren Buffet $4. His charitable history has "remained largely a mystery," $4 in 2017 after Bezos $4 for philanthropy on Twitter.

A nonprofit bearing Bezos's last name - the $4 - $4 to the Fred Hutchinson Cancer Research Center in Seattle. However, the fund $4 the Amazon CEO's parents, and reportedly hasn't received contributions from Jeff Bezos himself.

Additionally, Bezos had never appeared on the annual list of America's 50 largest donors - $4, when $4 with the launch of $4 for education programs for the homeless. Still, that donation $4 at the time.

Here are all the major donations Jeff Bezos is known to have given to charity since becoming a billionaire in 1997: