Maintaining sufficient levels of competition ranks among the core interests of any national – and increasingly international – antitrust policy; however, the formal proof that a cartel really functioned economically and did not only exist in a legal sense is hard to deliver: market power is...

This paper provides a textbook example of integration between commodity markets, and the subsequent price convergence or absence thereof. We analyze price relations between spot markets for natural gas in Europe. We apply time-varying coefficient estimation applying the Kalman filter, to test...