Vertical Arrangements, Market Structure, and Competition : An Analysis of Restructured U.S. Electricity Markets

This paper examines the relative importance of horizontal market structure, auction design, and vertical arrangements in explaining electricity prices. We define vertical arrangements as either vertical integration or long term contracts whereby retail prices are determined prior to wholesale prices. This is generally the case in electricity markets. These ex ante retail price commitments mean that a producer has effectively entered into a forward contract when it takes on retail customers. The integrated firm has less incentive to raise wholesale prices when its sale price is constrained. For three restructured wholesale electricity markets, we simulate two sets of prices that define the bounds on static oligopoly equilibria. Our findings suggest that vertical arrangements dramatically affect estimated market outcomes. Simulated prices that assume Cournot behavior but ignore this vertical scope vastly exceed observed prices. After accounting for the arrangements, performance is similar to Cournot in each market. Our results indicate that auction design has done little to limit strategic behavior and that horizontal market structure accurately predicts market performance only when vertical structure is also taken into account