This article examines the financial effects of shareholder pressure in what activists consider the visible and successful instance of social activism in investment policies, the boycott of South Africa designed to speed the end of the apartheid regime. It seems that socially activist shareholder pressure on corporations has become a fact of life. In 1987, the American Medical Association called on medical schools and their parent universities to divest tobacco holding stocks. The demand for stocks may be sufficiently elastic so that pressures by social activists merely redistribute ownership from socially active investors to other investors without affecting stock prices. South Africa itself may have switched to trading with other countries not participating in the boycotts at low cost. The alternative hypothesis is that activism and sanctions imposed measurable costs and constrained unique investment opportunities so that firm value was affected adversely. This alternative predicts that banks and corporations with South African operations and the South African financial markets experienced negative stock price reactions on the announcement of legislative and private investor sanctions.