The paper analyses the effects of competition and regulation policies on competitiveness. In the first part of the paper the literature on the welfare effects of competitive-enhancing policies is discussed. The conclusion of such literature is that a negative relationship between concentration and welfare does not always hold. Asymmetric information and other market failures could determine a positive relationship between concentration and welfare. The second part of the paper develops a model to show that regulation of a vertical integrated monopoly in a country is not necessary if there when competition between countries in final products (services) market. The last part of the paper analyses the methodological problems that arises when is empirically evaluated the effect of concentration on industrial sectors competitiveness.