§5 MARKET SHARES

105. Market definition enables the Commission to identify the suppliers and customers active on a relevant market. It can then calculate the total market size and the market share of each supplier, generally based on sales (and, for customers, purchases) of the relevant products in the relevant geographic area. 106. Market shares reflect the relative position of suppliers on the market and, as such, can be very useful in assessing market power. However, market shares are not the sole indicator of an undertaking’s strength in the market (144). Other factors, such as barriers to entry or expansion, including those derived from scale or network effects, access to specific assets and inputs, as well as product differentiation and degree of substitutability, may also be relevant, depending on the specific facts of the case. The Commission’s guidelines on substantive assessments in competition cases explain this further (145). 107. The Commission usually relies on market shares based on merchant sales (146). Conversely, in purchasing markets, the Commission usually relies on market shares based on (merchant) purchases. Generally, both the value of sales or purchases and the volume of sales or purchases provide useful information. 108. In addition to merchant sales or purchases, depending on the specific products or the specific industry in question, other metrics can provide complementary or more useful information to determine market shares. These may include: capacity or production (147) (in particular for markets characterised by the strategic importance of capacity) (148); the number of suppliers (in particular in markets involving formal calls for tender or in situations where innovative products are at the development stage); the number of contracts awarded (149); usage metrics such as the number of (active) users (150), the number of website visits (151) or streams, time spent or audience numbers (152), the number of downloads (153) and updates, the number of interactions (154) or the volume or value of transactions concluded over a platform (in particular where access to products is provided mainly at a zero monetary price, as can be the case in digital markets, or more generally in the case of multi-sided platforms); units of fleet, seat capacity, number of trips or access rights such as slots at specific airports (for instance in transport markets) (155); or reserves held (for instance in the mining sector) (156). In markets where there are frequent and significant investments in R&D, the level of R&D expenditure or the number of patents or patent citations may be used as relevant metrics to assess the relative competitive position of undertakings (157). Metrics used internally by market participants in their general course of business generally prove particularly relevant. 109. When markets are defined around customer locations, all sales to customers in the relevant geographic market are included in the calculation of market shares. Accordingly, sales by suppliers from other areas to customers in the relevant geographic market (that is to say imports into the relevant market) are included when computing market shares, while sales by suppliers located in the relevant market to customers located in other areas (that is to say exports from the relevant market) are excluded (158). By contrast, when markets are defined around supplier locations, all sales by the suppliers located in the relevant market are included in the calculation of market shares, regardless of customer location (159). Sales by suppliers located outside the relevant geographic market are excluded from the calculation of market shares in that case. 110. When products are significantly differentiated (as explained in 4.1), market shares may provide a less reliable indicator of market power, and, as part of its competitive assessment, the Commission generally also analyses whether the undertaking(s) involved and other suppliers compete closely. Therefore, although market definition remains an important step, analysing how closely suppliers compete may be more relevant than assessing market shares in the competitive assessment of differentiated markets (160). To that effect, the Commission may, where appropriate, rely on shares for segments of the relevant market and take those into account when assessing how closely the undertakings involved compete with each other and with their competitors (161). 111. Furthermore, when products are significantly differentiated, market shares measured in sales value and sales volume can be significantly different. The Commission usually considers sales values as a starting point (162). Nevertheless, sales volumes can complement sales value and may in some instances be better suited to assess the effects of the conduct or concentration under investigation. For example, in the case of a concentration involving two undertakings offering a product at a much lower price than other undertakings, but capturing a significant share of customers, sales value alone may underestimate the competitive importance and interactions of those undertakings (163). 112. Market share information may be provided in the form of estimates by the undertaking(s) involved, if precise market shares are not available to them. The Commission additionally or alternatively uses other sources of information on market size and market shares when necessary for the purposes of its assessment. These may include studies or reports by public authorities, industry consultants or trade associations, internal documents of the undertaking(s) involved or estimates provided by market participants. In particular where no reliable estimates from the undertaking(s) involved or information from other sources are available, the Commission may carry out a full or partial market reconstruction, through requests for information addressed to relevant market participants, asking the suppliers or customers in the relevant market to provide data on their own sales or purchase volumes or values, or other relevant metrics. In the Commission’s experience, such market reconstructions are generally more suitable for markets involving a limited number of suppliers. 113. As a general rule, the Commission relies on market shares computed over 1 year reference periods. The Commission usually collects such data for at least 3 years, or, in the context of enforcement of the antitrust rules, generally for periods corresponding to the duration of the investigated conduct. However, the reference period over which market shares are computed may differ from the standard 1 year period depending on the characteristics of the relevant market. In particular, in markets characterised by lumpy or irregular demand, or seasonality of supply and/or demand, or in markets undergoing structural change, it may be appropriate to compute market shares over longer or shorter reference periods (164). In markets undergoing structural transitions, such as regulatory or technological changes, or where a forward-looking assessment may be appropriate to capture the market dynamics, market shares may be estimated for the future to reflect those expected changes (165).

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Source: EUR-Lex (Cellar) · retrieved 2026-09-07