A vertically integrated firm that wholesales to its retail rivals can, if it has sufficient market power, set the margin between its retail and wholesale prices so as to harm its rivals. Conventionally, an imputation test is used to determine whether such behavior is being undertaken. Such tests...

Next generation access networks (NGANs) are in many cases likely to be supplied by vertically integrated firms, that is, firms that both wholesale access and sell services downstream to end-users. A long standing concern of regulators is that such firms may engage in anti-competitive price...