$700 billion. That’s how much banks and other financial service providers could generate in additional annual revenue if they do nothing more than provide financial services to women at the same rate they are provided to men. In overlooking the women’s market, the financial industry is missing out on an enormous business opportunity. To put this $700 billion opportunity in context, that’s almost double the size of Elon Musk’s net worth.

Nearly one billion women around the globe are completely excluded from the formal financial system even though, in most of the world, women wield considerable influence in financial and purchasing decisions as household finance managers or business owners. Financial service providers, particularly in the emerging markets, have been very slow to design products that meet women’s needs and are leaving a lot of money on the table in doing so. This inertia is certainly not in their best interest: Women are loyal clients for financial service providers; in developed markets, 61 percent of female customers stay more than five years with a bank compared with 46 percent of male customers. Women typically have better loan repayment rates than men and are less likely to “bounce” checks; likewise, they tend to be longer-term, “stickier” savers and typically build higher savings to income ratios than men.

The gender gap in access to business capital provides a particularly rewarding opportunity. There are 12 million women-owned micro, small & medium enterprises (MSMEs) in the world, more than half of which are in the developing world. Seventy percent of these female entrepreneurs report inadequate access to growth capital, representing an unmet financing need that totals a whopping $17 trillion. This market failure is driven by a combination of regulatory obstacles and restrictive social and cultural norms, in addition to the overall lack of financial products that work for women.

In my recently released book, There’s Nothing Micro about a Billion Women: Making Finance Work for Women, I illustrate through the personal stories of numerous female clients in emerging markets that underserved women are a lucrative customer segment. The book lays out a convincing business case for closing the gender gap in financial services and explores the powerful macroeconomic benefits that would accompany women’s full inclusion in the financial system.

Read the full article about women in finance by Mary Ellen Iskenderian at Stanford Social Innovation Review.