The Pure Capital-Cost Barrier to Entry
提出两种原因（非融资市场固定成本）导致纯粹资本成本进入壁垒，该壁垒使集中市场中的在位企业能长期获得超额利润，并提供了支持证据。
A barrier to entry is a structural trait of a market implying that incumbent sellers can earn more than a normal rate of return without attracting entry (Bain, 1956; 1968, chapter 8). As regards capital costs, incumbents may have an absolute cost advantage because barriers to entry resulting from product differentiation, economies of scale, or impacted technological information increase the uncertainty enveloping the potential entrant's investment decision (Caves and Porter, 1977). This paper (1) advances two causes (other than fixed costs of entering markets for funds) for a pure capital-cost barrier to entry, (2) shows that barrier implies both (a) the coincidence of seller concentration with long-run excess profits and (b) a direct relation between concentration and excess profits even if the ability to coordinate price and nonprice rivalry were held constant over observed levels of seller concentration, and (3) provides evidence supporting the existence of such a barrier. In a market with multi-plant economies of in noncapital-raising aspects of production,' product differentiation, afsolute cost advantages other than those associated with capital costs, and financial markets which priced assets to provide an expected rate of return commensurate with risk, incumbent firms can elevate price above average costs without inducing entry if the post-entry capital costs for all firms in the industry exceed the pre-entry costs. Even in the absence of fixed costs of entering markets for funds, there are reasons for such a difference in costs. First, Sullivan (1978) has found that the systematic risk resulting from the stock market's revaluation of assets in response to new information is less for firms in concentrated industries than for those operating in more competitive markets. He suggests that may be because of the ability of large firms in concentrated industries to mitigate the adverse effects of new bearish information. His conjecture might be supported and extended by building oii the attempt of Salamon and Siegfried (1977) to establish links among elements of market structure and measures of political clout. For example, political influence might enable a firm to avoid the full impact of an economy-wide increase in taxes. Second, a different hypothesis is advanced in Scott (1977, 1980). Sullivan's work is based on the capital asset pricing model (CAPM), for which investors' general expected utility maximization problem has been reduced to a choice over two parameters of subjectively-evaluated probability distributions of returns. But, ceteris paribus,the probability distributions of returns in concentrated industries offer downside protection and upside potential relative to unconcentrated industries. That skewness could imply lower capital costs for firms in concentrated industries. To develop the skewness possibility, suppose that the stochastic process generating market demand is in general a Markov chain with large diagonal elements in the transition matrix.2 While that stochastic process together with existing capacity can imply the probability of capacity shutdown at any future time, adding market structure to the picture implies the probability thatfirms will exit during various periods of time. The probability that any given number of firms will exit varies inversely with seller concentration. Even if investors could diversify costlessly, the extra flexibility given market power to choose a profitable price and output in the face of a downturn in demand and the difference in costs-resulting from bankruptcy costs-for capacity shutdown versus firm exit can imply that capital costs fall as seller concentration increases. Thus, this paper suggests two reasons (other than Sullivan's political power speculation or fixed costs of transacting in financial markets) why the cost of capital of firms in concentrated industries could, ceteris paribus, be lower than for firms in unconcentrated industries. The two reasons follow from the fact that in an industry with fixed capacity and variable demand, a reduction in demand at a point in time may force firms to exit. But the probability of forced exit of a given firm is directly related to the number of firms in the industry. Hence, increased market concentration results in the reduced probability of forced exit. The reduction in that probability reduces capital costs by Received for publication January 23, 1980. Revision accepted for publication November 7, 1980. * Dartmouth College. I thank two anonymous referees of this REVIEW for very helpful comments on an earlier version of this paper. ' Thus by no economies of scale I do not mean costless and instantaneous adjustment to any point on a horizontal average cost curve. Capacity does come in discrete chunks (plants) for which we have the usual U-shaped cost curves. However, regardless of the number of these plants producing at minimum average cost that are combined to make a firm, unit cost is the same. Further, at the current levels of market demand, these units of capacity need not be large relative to the output of the market. That is, there need not be a scaleeconomies barrier in the sense of Bain. 2 Market demand has a high probability (but less than one) of staying where it currently is. If demand should fall, the fact that it is unlikely to rebound will force a reduction in capacity.