Supply Function Equilibria and Nonprofit-Maximizing Objectives

We examine the supply function equilibrium (SFE), which is often used in the analysis of multi-unit auctions such as wholesale electricity markets, among (partially) public firms. In a general model, we characterize the SFE of such firms and examine the properties of symmetric SFE. We show, analyzing an asymmetric SFE in a duopoly model with linear demand and quadratic cost functions, that, when a partially public firm weighs more on the social welfare, the supply functions of not only the partially public firm but also a profit maximizing firm are flatter at the equilibrium. We also confirm that in a linear-quadratic model, the SFE converges to the (inverse) marginal cost function when the firms' social concerns increase symmetrically in the industry.