Book excerpt: How effectively can governing mechanisms forged before the surge of activist investment continue to protect shareholders and efficiently order capital markets? This is a pressing question for scholars and practitioners of corporate law, as well as for market participants generally. In order to illuminate the extent to which the growing trend of shareholder activism calls for a new understanding of the kind of shareholder-corporate relations the law should facilitate, this book introduces the concept of shareholder-driven corporate governance. This concept refers to the evident phenomenon of shareholder involvement in corporate governance and offers a normative endorsement of this development. In order to secure the benefits of investors' increasing involvement in corporate affairs, regulatory regimes must grapple with a number of considerations. This book is based on the idea that shareholder corporate governance is a welcome development, but that it does not come without regulatory challenges. For one, it requires rejecting the idea that well-ordered capital markets can be achieved through corporate law which is subservient to private ordering. The mandatory character of, for example, securities regulation is vital to fostering shareholder involvement in corporate affairs. Defenders of shareholder corporate governance must also confront the matter of "wolf packs," or loosely formed bands of investors who defy existing regulatory categories but nonetheless exert collective influence. Regulation that is sensitive to both the inadequacies of past approaches to corporate-shareholder relations and the novel challenges posed by increasing shareholder activism will be able to harness activism, allowing capital markets to flourish.