Assigning Market Shares for Antitrust Analysis (G.J. Werden). Introduction. The role of market shares in antitrust analysis. Common denominators for assigning market shares. Structural and equilibrium market shares. Asset-based market shares. Output-based market shares. Imports and exports. The problem of attribution. Conclusions. References. Mergers Among bidders with correlated Values (L. Froeb, S. Tschantz). Introduction. Families of mixing distributions. Mixtures of power-related distributions. Conclusion. References. Measuring the Effect of Cartelization in Medicine: An International Study (P. Zweifel, C. Nicolet). Introduction. Theoretical considerations. Indicators of power. Testing the hypotheses. Discussion and conclusion. References. Spatial Economics and Market Definition (F.M. Scherer). Introduction. Testimony. Market Power and Simultaneous Recoupment in the Maryland Medical Electronic Claim Submission Market (D.I. Rosenbaum, J.P. Lenich). Introduction. Blue Cross Blue Shield of Maryland and EDS. The Martello litigation. The legal standards. Relevant market. Barriers to entry. Market power. The predation scheme. Conclusion. Appendix. Measuring Market Power in the Steel Industry (E. Maasoumi et al.). Introduction. A framework for measuring market power. Geographic and product market definition. Assesing the degree of competition and market power. Conclusion. References. Measuring Market Power and Competition Policy in Hong Kong (P. Lin, E.K.Y. Chen). Introduction. The Consumer Council's studies of market power. Hong Kong's competition policy. Concluding remarks. References. Staples-Office Depot and UP-SP: An Antitrust Tale of Two Proposed Mergers (L.J. White). Introduction. The Staples-Office Depot merger. The UP-SP merger. Conclusion. References. How Digital Economics Revises Antitrust Thinking (R.B. McKenzie, D.R. Lee). Introduction. Key concepts in digital economics. The role of market dominance. The measure of market share. Demand-side scale economies. The benefits of switching costs and lock-ins. The dominant producer's demand for antitrust enforcement. Complementary goods. Role of Cartels. Multiple outcomes. Concluding comments. References. Raising the Costs of Unintegrated Rivals: An Analysis of Barnes & Noble's Proposed Acquisition of Ingram Book Company (D.S. Sibley, M.J. Doane). Introduction. Overview of market participants. Simulating B&N's incentive to raise rivals' costs. Conclusion. References. Mergers and Market Power: Estimating the Effect on Market Power of the Proposed Acquisition by the Coca-Cola Company of Cadbury Schweppes' Carbonated Soft Drinks in Canada (A. Abere et al.). Introduction. CSDs in Canada. Approaches to identifying an SLC in a merger. Demand systems. Estimation of demand systems in Ontario. Implementing the hypothetical monopolist test. Price simulations. The Bureau's case. Conclusion. References. Geographic Market Limits for Yellow Pages Advertising in California (J.M. Riddle, W.S. Comanor). Introduction. The cross-price elasticity standard. The Merger Guidelines standard. Using prices to delineate geographic markets for Yellow Pages advertising. Contiguous market areas and the Merger Guidelines standard. Concentration and market power. Concluding comments. References. Market Power in the US Airline Industry (J.C. Weiher et al.). Introduction. Data. Costs. Market power measures. Market power by market structure. Conclusions. References.