Assigning a hard and fast dollar value to philanthropic gifts isn't nearly as straightforward as it sounds. Many donors work hard to keep gifts quiet, public information is incomplete, and gifts of stock can swing in value. So to compile BusinessWeek's annual ranking, a team of reporters scours news reports, foundation filings, and online IRS filings, and conducts countless interviews. It takes months of work to compile our annual list of the 50 Most Generous Philanthropists.
As we've done every year since launching the survey in 2002, we rank givers by what they've pledged and given in the past five years. We count pledges because we think philanthropists who make legally binding promises deserve to be recognized. We also estimate lifetime contributions and present those figures as a percentage of a person's current net worth. For consistency, we count all pledges at the value at the time they were initially announced, discounting only those that have been formally revoked.