Decomposing changes in competition in the Dutch electricity market through the Residual Supply Index

We propose to assess the influence of a number of events on the degree of competition in the Dutch electricity wholesale market over the period 2006-2011 through a decomposition method based on the Residual Supply Index. We distinguish regulatory market-integration events, firm-level events and changes in the level of residual demand. We conclude that market-integration measures to improve competition have been effective, but that the changes in residual demand appear to have been equally important. Firm-level events have only had a minor impact on the intensity of competition.