Global inequality is growing. Financial markets disenfranchise women, the 99 percent, and the planet itself. But what if we found the source of power and turned it inside out? What if we made the tools of the system available to all? When she launched the world's first stock exchange for social enterprises, Durreen Shahnaz started more than a new financial system; she sparked a movement. Defiant optimism--the stubborn belief that systems that enrich the few can be transformed for the good of the many--requires an indomitable spirit. In these pages, Shahnaz illuminates what investing in those excluded from networks of power and opportunity requires. From growing up with constrained life chances, to working as the first Bangladeshi woman on Wall Street, to becoming a global leader in impact investing, Shahnaz takes us on a mesmerizing trek of innovation, compassion, and enterprise. We accompany her to villages in Bangladesh where she helps women entrepreneurs learn to proudly sign their names, and on visits to venture capitalists who walk past her to shake her male employees' hands. We go to a garment factory where women labor for low wages, and to a town in India where microfinance offers women enough capital to run grocery stores and tailor shops. Along the way, the birth of her two daughters only fuels her relentless pursuit of a world where girls are valued. Finally, armed with financial backers and a plan, Shahnaz crafts the world's first tradeable financial product geared toward investing in underserved women's livelihoods. Changing how systems work--and who they work for--isn't for the faint of heart. But The Defiant Optimist offers strategies for placing women, the underserved, and the planet at the heart of systems. Together we can locate the levers of power and pull them defiantly in a new direction.