Warren Buffett ... convened the first-ever Forbes 400 Summit on Philanthropy, a gathering of 161 billionaires and near-billionaires intent on solving the world's most intractable problems.

The U.S. has the most with 902 billionaires ... according to Forbes' recently released 2025 World's Billionaires List, including Warren Buffett, pictured here. Warren Buffett is the CEO of ...