This paper is concerned with the problem of price regulation when demand is uncertain. Uncertainty gives rise to substantial difficulties in determining both the return a firm's owners should be provided and a set of prices capable of producing that return. We argue that conventional approaches to price regulation are incapable of attaining the economically desirable objectives of efficiency and an equitable return to investors. The deficiencies in current practices are attributable to the separation of the risk measurement-return determination and price setting activities in the conventional approach. We present a model of the regulated firm that synthesizes contemporary financial market theory and the theory of the firm under uncertainty.1 In our approach, the income stream produced by the firm is valued ex ante in the financial market according to investors' perceptions and preferences over risk-return characteristics. We portray the firm as producing risk and return by choosing among available production technologies to maximize its market value, given the prices set by regulators. Within this framework, it is shown that regulators can choose the lowest prices consistent with an equitable return to investors. We also show that prices so chosen induce the choice of the optimal technology by the firm.