Why define markets in competition cases?
Stellenbosch Working Paper Series No. WP10/2013Publication date: 2013
Author(s):
Competition policy investigations usually commence with a definition of the relevant product and geographic market. The relevant market provides a first evaluation of competitive conditions and allows for the calculation of market shares, which aids in the assessment of firms’ market power. Given its implications for assessing market power, the market definition in a competition case is frequently contested. Critics argue that market definition is often arbitrary and should be avoided. Instead, IO scholars argue that modern econometric methods are capable of directly estimating market power and competitive effects without the need for defining markets. We argue that market definition not only offers a valuable first screen for market power, but actually involves a substitution analysis that lies at the heart of any competition case. We argue that it is suboptimal to promote a single encompassing econometric model instead of the multi-faceted empirical approach underlying most market definition exercises in practice. In addition, we note that market definition involves much more than merely the estimation of price elasticities, which are in any event difficult to estimate in most competition cases.
JEL Classification:L11, L40, L41, K21
Keywords:market, market definition, market share, substitutability, price elasticity, antitrust, competition policy, mergers, monopolization
Download: PDF (150 KB)Login
(for staff & registered students)
Upcoming Seminars
Monday 21 July 202512:00-13:00
Izak Odendaal: Old Mutual Wealth Chief Investment Strategist
Topic: "Diverging fiscal policies and what it means for markets"
12:00-13:00
Dr Neil Rankin: Ceo Of Predictive Insights & Stellenbosch University
Topic: "TBC"
12:00-13:00
Prof Willem Boshoff: Stellenbosch University
Topic: "Two competing approaches in South African competition policy: merger control and anti-cartel enforcement over the past 30 years"
BER Weekly
27 Jun 2025 Another setback for the GNU, but oil markets breathe a little easierThis week was marked by heightened tensions both domestically and internationally. At home, friction intensified between the two largest parties in the Government of National Unity (GNU), the ANC and the DA, following the firing of one of the DA's deputy ministers. Internationally, the US conducted airstrikes on three Iranian nuclear facilities using...
Read the full issue
Upcoming Seminars
Monday 21 July 202512:00-13:00
Izak Odendaal: Old Mutual Wealth Chief Investment Strategist
Topic: "Diverging fiscal policies and what it means for markets"
12:00-13:00
Dr Neil Rankin: Ceo Of Predictive Insights & Stellenbosch University
Topic: "TBC"
12:00-13:00
Prof Willem Boshoff: Stellenbosch University
Topic: "Two competing approaches in South African competition policy: merger control and anti-cartel enforcement over the past 30 years"
BER Weekly
27 Jun 2025 Another setback for the GNU, but oil markets breathe a little easierThis week was marked by heightened tensions both domestically and internationally. At home, friction intensified between the two largest parties in the Government of National Unity (GNU), the ANC and the DA, following the firing of one of the DA's deputy ministers. Internationally, the US conducted airstrikes on three Iranian nuclear facilities using...
Read the full issue