Sustainable investing has never been more influential—or more contested. More than 5,000 investors controlling $140 trillion have committed to investing sustainably, yet a troubling paradox has emerged: many self-proclaimed sustainable investors don't actually invest sustainably, and the real-world impact of ESG strategies is far more limited than their advocates admit.

Big Money, Better World? cuts through the noise. Drawing on rigorous academic research and the author's experience as Head of Sustainable Investing, the book offers an honest, evidence-based account of what sustainable investing is, how it works, and where it falls short.

The culprit, the book argues, is “hedgehog thinking”: dominant ESG strategies that rally around a single big idea—portfolio decarbonisation, ESG ratings, impact monetisation—and treat it as the answer to everything. These approaches oversimplify the complex, interconnected reality of sustainable development and risk diverting capital from where it matters most.

The antidote is a “foxy” mindset: plural, adaptive, and grounded in sustainability science. The book shows how asset allocation, active ownership, and field-building can drive genuine corporate and systemic change—without sacrificing returns. It will be of interest to investors, policymakers, researchers, and engaged citizens ready to move beyond the hype.

Jan Anton van Zanten is Head of Sustainable Investing at Osmosis Investment Management NL and Visiting Fellow at Erasmus University Rotterdam. He holds a PhD from Erasmus University and an MPhil from the University of Cambridge. Previously Executive Director and SDG Strategist at Robeco, he aligned multi-billion euro portfolios with the UN Sustainable Development Goals. Earlier, he advised multinationals at Steward Redqueen and contributed to climate resilience work at the UN Environment Programme. His research appears in the Financial Analysts Journal, Organization & Environment, and Journal of International Business Policy, among others.