10 Years after the failure of Lehmans, the finance sector is now often seen as a potential ally in promoting sustainability. Green bonds and impact investment are growing trends with the promise of financing renewable energy, catchment management and more. But can the finance sector model of pile it up and sell it cheap work with the complexity and uncertainty which is often central to sustainability? Even if it can, the finance system demands economic growth to feed returns to investors and lenders which doesn’t sound particularly sustainable. Furthermore it is hardly a sector that is known for its trustworthiness. Can these circles be squared? Can we develop a financial system that truly promotes sustainability?