Although the nationalizations broke up the concentration of economic power that had been held by financial-industrial groups, the subsequent merger of several private firms into single publicly owned enterprises left domestic markets even more monopolized. Apart from special cases, as in iron and steel, where the economies of scale are optimal for very large firms, there was some question as to the desirability of establishing national monopolies. The elimination of competition following the official takeover of industries such as cement, chemicals, and trucking probably reduced managerial incentives for cost reduction and technical advance.