The financial crisis of 2008 is a looming figure in current economic thinking. The global economy is still slowly recovering from the shock, and policymakers and academics continue to discuss the structural changes needed to prevent a recurrence. The stress of the last half decade has made two things very clear: A productive and innovative financial system is essential to the broader economy, but financial innovations made irresponsibly—without consideration of systemic risk and other impacts on society—can wreak havoc.