Today, “mobile money” - a service enabling people to send, receive, and store money on a cellphone - allows a market trader in Kenya to borrow a modest amount at sunrise to buy her stock, and then pay it back at sunset from her daily earnings. This seemingly simple micro-level exchange has the power to support livelihoods, increase access to health and education, and improve the lives of people in every country. And the digital revolution in financial technology, or fintech, is extending the reach of finance in into many other new domains.

By the end of 2020,...