Defining Market Dominance: A Study of Antitrust Decisions on Business Acquisitions in New Zealand

Information from the 207 decisions of the New ZealandCommerce Commission on business acquisitions for1991–96 are used to test how the Commission assessedmarket dominance. Dominance is found to emerge whereboth the market share of the merged entity and theentry barriers were high. A probit regression modelsuggests that there was a 50% probability thatdominance would be found when market share was 75%,in a market where the entry barrier was high. Theapplication of the US merger guidelines to a sub-setof markets finds that the dominance threshold ofanti-competitiveness applied to New Zealand mergerswas very much more lenient than the substantiallessening of competition threshold used in the U.S.