"I resist the temptation of asking you to guess how many people are actually excluded. Two billion people worldwide remain without a bank account; two billion people do not have a bank account.
"Now, there has been improvement, because it's 20 percent less over the last three years, but still two billion is a massive number," the IMF Managing Director said at the Institute for New Economic Thinking Conference on Finance and Society.
"For example, even here in the United States, surveys find that some eight per cent of US households are un-banked, and some 20 per cent are under-banked," Lagarde said.
Studies show that broader access to the financial system can boost job creation, increase investment in education, and help people manage risks and absorb financial shocks better, she argued.
More From This Section
An IMF analysis, that will be released later in the autumn, finds that financial inclusion is particularly important, for women, empowering them economically and allowing them to invest in education, which they do a lot more than their male counterparts, she asserted.
"This gap is even bigger if one considers the role of women in the provision of financial services," she said.
"Yet desirable as it is, as an objective, financial inclusion is not without risks, particularly if it leads to excessive financial risk-taking.
"Our forthcoming analysis shows that if supported by good regulation, good supervision, and independent supervision, financial inclusion can actually go hand-in-hand with financial stability," Lagarde said.
"So in conclusion, the financial crisis has exposed several fault lines and provided many lessons. An overarching lesson is that building sustainable and inclusive growth hinges on collaborative efforts.