Estimating market power is often complicated by a lack of reliable marginal cost data. Instead, policy-makers often rely on summary statistics of the market, thought to be correlated with price cost margins? such as concentration ratios or the HHI. In many industries, these summary statistics...

As with other commodities, electricity is often traded on both forward and spot markets. This was initially true in the restructured California electricity industry from 1998 to 2000. Though the power traded in the forward and spot markets was for delivery at the same times and locations, prices...