How Chronicle of Philanthropy compiled list of top 50 donors

The 21st annual Philanthropy 50, the Chronicle of Philanthropy’s list of America’s biggest donors, is based on gifts and pledges of cash, stock, land and real estate to nonprofit organizations in 2020.

The Chronicle talked to dozens of nonprofits, philanthropists and their representatives to find out more about large donations that were made public last year, as well as the philanthropy of big donors who gave quietly. However, not all philanthropists publicly disclose details about their giving, and they are not legally required to do so.

Gifts made to donors’ family foundations and donor-advised funds were counted; however, disbursements from those grant-making vehicles were not included in our rankings to avoid double-counting.

The Chronicle counts only gifts that donors make to organizations with charity or foundation status under section 501(c)(3) of the Internal Revenue Code.

Some of America’s biggest donors don’t appear on the current Philanthropy 50 even if they have made a big gift to a nonprofit last year. That’s because the Chronicle’s rankings count multiyear pledges only once, as a lump sum in the year the commitment was made.

For example, Warren Buffett is absent from this year’s list even though he gave the Bill & Melinda Gates Foundation stock in his Berkshire Hathaway investment firm valued at more than $2.2 billion last year.

The donation was an annual installment on his 2006 pledge of more than $36 billion in Berkshire shares to the foundation. That same year he also made multibillion pledges to the foundations of his late first wife and his three children.

Here’s how much Buffett gave to charity last year:

— Nearly 12.2 million shares of class “B” Berkshire stock valued at more than $2.2 billion to the Gates Foundation,...