Researchers Daryl Collins, Jonathan Morduch, Stuart Rutherford, and Orlanda Ruthven spent 10 years studying the financial lives of the lowest classes of Bangladesh, India, and South Africa.
A fundamental finding that they include in "Portfolios of the Poor" is that extreme poverty flourishes in areas not where people live dollar to dollar or where poor purchasing decisions are widespread, but instead arises where they lack access to financial institutions to store their money.
"It's mind-blowing that almost half the world — almost 3 billion people — live on $2.50 a day or less. More than one billion people live on $1 a day or less," Zuckerberg writes. "I hope reading this provides some insight into ways we can all work to support them better as well."