Can big companies fix big problems? Are they responsible for doing so? As the third-largest employer in the world, any move Walmart makes reverberates around the globe. Yet despite its many successes and innovations, particularly in terms of sustainability, the company often faces criticism for its business practices. Harvard Business School professor Rebecca Henderson discusses what she calls the paradigmatic case: how Walmart takes huge risks, makes great strides, and demonstrates how companies are one of the few instruments humanity has for changing the world at scale, for better or for worse.