Warren Buffett and Bill and Melinda Gates are asking hundreds of rich Americans to pledge at least 50% of their wealth to charity.

True if, as of 2010, Buffett and Bill and Melinda Gates were jointly running an effort, the Giving Pledge launched in 2010, that asked wealthy Americans to pledge at least 50% of their wealth to charity, and the outreach was aimed at a large group on the order of hundreds. Mostly true if the joint effort and the 50% threshold are right but a minor detail differs, such as the number of people approached being somewhat below 'hundreds' or some outreach being aimed at non-Americans. Mixed if the campaign existed but a core element is wrong, such as a different threshold or Melinda Gates not being involved. Mostly false if a related effort existed but differed substantially from the description, for example informal dinners only, with no pledge being sought. False if evidence shows no such solicitation effort existed in 2010.

Set before the research began.

1. E1 More U.S. billionaires pledge to give away wealth Raw Story (Reuters US Online Report) · 9 December 2010

   “Gates, his wife Melinda, and Buffett have asked U.S. billionaires to give away at least half their wealth during their lifetime or after their death, and to publicly state their intention with a letter explaining their decision.”

2. E2 More U.S. billionaires pledge to give away wealth Raw Story (Reuters US Online Report) · 9 December 2010

   “Along with speaking to about a quarter of the wealthiest people in the United States about The Giving Pledge, Gates and Buffett hosted a dinner with Chinese billionaires”

3. E3 U.S. billionaires pledge fortunes to charity - Stabroek News Stabroek News (Reuters) · 5 August 2010

   “Dozens of U.S. billionaires pledged yesterday to give at least half their fortunes to charity as part of a philanthropic campaign”

4. E4 Our Story - The History of the Gates Foundation Gates Foundation · 28 February 2020 Own record

   “Bill and Melinda Gates join Warren Buffett to create the Giving Pledge, an effort to encourage America’s wealthiest families to donate the majority of their wealth to philanthropic causes and charities.”

Independent Reuters reporting [E1] confirms that Bill Gates, Melinda Gates and Buffett asked U.S. billionaires to pledge at least half their wealth to charity. [E3] confirms the campaign was running in 2010, and dozens had pledged by August. [E2] says they spoke to about a quarter of the wealthiest people in the U.S., which does not clearly establish outreach to 'hundreds', and it notes outreach to Chinese billionaires as well. The joint effort and the 50% threshold are confirmed, while the scale and the purely American focus are less certain.