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Yan Yang

Date of Award


Author's School

School of Law

Degree Name

Doctor of Juridical Science (SJD)

Degree Type



Market definition is an important component in the premerger investigation, but the models used in the market definition have not developed much in the past three decades since the Critical Loss Analysis (CLA) was proposed in 1989. The CLA helps the Hypothetical Monopolist Test to determine whether the hypothetical monopolist is going to profit from the small but significant and non-transitory increase in price (SSNIP). However, the CLA has long been criticized by academic scholars for its tendency to conclude a narrow market. Although the CLA was adopted by the 2010 Horizontal Merger Guidelines (the 2010 Guidelines), the criticisms are likely still valid. In this dissertation, we discussed the mathematical deduction of CLA, the data used, and the SSNIP defined by the Agencies. Based on our research, we concluded that the narrow market conclusion was due to the incorrect implementation of the CLA; not the model itself. On the other hand, there are other unresolvable problems in the CLA and the Hypothetical Monopolist Test. The SSNIP test and the CLA are bright resolutions for market definition problem during their time, but we have more advanced tools to solve the task nowadays. In this dissertation, we propose a model which is based directly on the multi-dimensional substitutability between the products and is capable of maximizing the substitutability of product features within each group. Since the 2010 Guidelines does not exclude the use of models other than the ones mentioned by the Guidelines, our method can hopefully supplement the current models to show a better picture of the substitutive relations and provide a more stable definition of the market.

Chair and Committee

Johh N. Drobak, Supervising Professor, Committee Chair, Gerrit De Geest, Examining Professor; Peter K. Cramer, Examining Professor.

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