Screening for partial collusion in retail electricity markets

Starting from a theoretical model of coalition formation, we analyse which price markers are more adequate to identify clues of partial cartels. Based on the theoretical model, we argue that measures of the shape of a distribution (such as kurtosis and skewness) can complement centrality measures (such as the mean and the dispersion of the distribution of prices) to screen for potential partial cartels. We apply these price markers to price data from the Norwegian retail electricity market. •We propose price markers for the screening of partial cartels.•The price markers are based on kurtosis and skewness.•The price markers are founded on the theory of coalition formation.•We apply these markers to the Norwegian retail electricity market•We present evidence of periods consistent with a breakdown of a partial cartel.