The welfare effects of entry: the role of the input market

In a successive Cournot oligopoly, we show the welfare effects of entry in the final goods market with no scale economies but with cost difference between the firms. If the input market is very concentrated, entry in the final goods market always increases welfare. If the input market is moderately concentrated, entry in the final goods market reduces welfare if the entrant is moderately cost inefficient than the incumbents. If the input market is highly competitive, entry in the final goods market reduces welfare if the entrant is very much cost inefficient than the incumbents. Hence, entry in the final goods market is more desirable under a concentrated input market. It follows from our analysis that entry increases the profits of the incumbent final goods producers if their marginal costs are sufficiently lower than the entrant’s marginal cost.