Jurisdiction(s):
United Kingdom

Market power assessment checklist: market shares, HHI, entry and expansion barriers, switching and capacity constraints, and countervailing buyer power (mergers and dominance)

Published by a LexisNexis Competition expert

Checklists

This checklist summarises the factors relevant to assessing an undertaking’s market power. Such analysis is pertinent not only to mergers but also, for example, to determining whether an undertaking is to be regarded as dominant.

Does an undertaking have market power?

When evaluating market power, the following should be considered. Not every factor needs to be applied in each instance; ultimately, a case-by-case assessment, grounded in the characteristics of the relevant market, is required.

Market position of undertaking and its competitors

Calculation of market shares is ordinarily the starting point of any assessment
- The larger the market share, and the longer it is sustained, the greater the likelihood that the undertaking holds a dominant position
- 50% market share or more: generally evidence of the existence of a dominant market position
- 40–50% market share: may indicate market power, but this depends on additional considerations
- Below 40% market share: dominance is unlikely...

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Web page updated on 20/05/2026

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