HP-2020-000016 - [2025] EWHC 1451 (Ch)

It is well-established that market shares are a proxy for measuring market power. The Commission’s 2009 Guidance on its enforcement priorities in applying Article 102 TFEU (the Article 102 guidance) comments at §13:

“Market shares provide a useful first indication for the Commission of the market structure and of the relative importance of the various undertakings active on the market. However, the Commission will interpret market shares in the light of the relevant market conditions, and in particular of the dynamics of the market and of the extent to which products are differentiated. The trend of development of market shares over time may also be taken into account in volatile or bidding markets.”

In broad terms, as summarised in Bellamy & Child, European Union Law of Competition (8^th ed, 2018), §10-028 a market share of above 40% is typically regarded as a significant factor in evidencing dominance; and market shares significantly and consistently above 50% are likely to be strong indicators of dominance save in exceptional market conditions. Dominance is not likely if the undertaking’s market share is below 40%, unless there is specific evidence such as substantial disparities in market share and/or significant barriers to entry.

Market shares are typically assessed over one year reference periods, assessed for the duration of the conduct under investigation. There is, however, no inflexible rule as to the reference period that will be relevant in a given case, and it may, in particular cases, be necessary to consider market shares over longer or shorter reference periods: Market Definition Notice, §113.

Market shares cannot, however, be used simplistically in the assessment of dominance. While the defined market allows the identification of the closest competitive constraints on the undertaking under scrutiny, it will also be relevant to consider the extent of competition from products outside the defined market, while bearing in mind that such products will be more remote constraints: Market Definition Notice §17. That is particularly the case in a market where products are significantly differentiated.

It is also always necessary to have regard to the features of the market, because the importance of the market share as evidence of a dominant position will vary from market to market, according to the structure of the market. It is therefore necessary to consider the market share in the context of the nature of the market: Socrates, §§120–1, citing Case 85/76 Hoffmann-La Roche EU:C:1979:36, §40. Factors typically taken into account in the assessment of dominance are barriers to expansion, entry and exit, the countervailing power (if any) of competitors, customers and consumers, and the stability of the market share of the allegedly dominant undertaking.

The conduct of the undertaking alleged to be dominant may also be a relevant factor. As the European Court noted in United Brands, §68, in considering the competitive situation on the relevant market “it may be advisable to take account if need be of the facts put forward as acts amounting to abuses without necessarily having to acknowledge that they are abuses.” In Case T-30/89 Hilti v Commission EU:T:1991:70, §19, the General Court thus observed that “Hilti’s commercial behaviour bears witness to its ability to act independently of, and without due regard to, either competitors or customers in the markets in question.” If there is evidence that the relevant undertaking has been able to impose terms that disregard the wishes of its consumers, that is the “hallmark of dominance”: Genzyme v OFT [2004] CAT 4, §255. Each case will, however, turn on its own facts, and the factors relevant in one case may not be the same as the factors that will be relevant in another case.