How many cartels are there? The answer is important in assessing the efficiency of competition policy. We present a Hidden Markov Model that answers the question, taking into account that often we do not know whether a cartel exists in an industry or not. Our model identifies key policy...

We study cartel contracts using data on 18 contract clauses of 109 legal Finnish manufacturing cartels. One third of the clauses relate to raising profits; the others deal with instability through incentive compatibility, cartel organization, or external threats. Cartels use three main...