DP5000 Welfare Trade-Offs in US Rail Mergers
Since the publication by Williamson (1968) of his seminal paper on antitrust there has been a growing recognition by regulators of the need to assess trade-offs between merger-related efficiency gains and merger-induced increases in market power. This paper addresses that need by presenting a structural econometric model of recent mergers in the US rail industry. The paper extends the structural methodology by evaluating actual (as opposed to simulated) merger effects and by incorporating parametric estimates of merger efficiencies. Our empirical finding is that consumer surplus in US rail freight markets increased by about 30% between 1986 and 2001 despite dramatic industry consolidation, suggesting that to date the Williamson trade-off has favoured rail customers. We find that behaviour in these markets is consistent with the Kreps-Scheinkman (1983) model of a two-stage game where capacities are chosen first and then prices are set to give the Cournot outcome.
