Is 40% market share automatically dominant?

No. Market share above 40% is indicative but not conclusive. Courts and authorities consider: barriers to entry, buyer power, market definition, and economic evidence of market power. A 40% share in a contestable market may not confer dominance.

What is the Herfindahl-Hirschman Index (HHI) and when is it used?

HHI = sum of squared market share percentages. Below 1,500: unconcentrated. 1,500–2,500: moderately concentrated. Above 2,500: highly concentrated. US Merger Guidelines raise concerns for mergers raising HHI by >200 in a concentrated market.

ICN Dominance Threshold >40% Market Share

How It Works

Assess presumptive market dominance based on market share thresholds: EU Commission presumes dominance > 50% and rebuttable below 40–50%; UK CMA uses 40%+ as indicative; US DoJ uses 50%+. Includes HHI concentration analysis

Each component has a specific meaning:

Market share thresholds: EU Commission presumes dominance > 50% — The market share thresholds: eu commission presumes dominance > 50% recorded for the scenario being assessed.
Rebuttable below 40–50%; UK CMA uses 40%+ as indicative; US DoJ uses 50%+ — The rebuttable below 40–50%; uk cma uses 40%+ as indicative; us doj uses 50%+ recorded for the scenario being assessed.

Note: Interpret the dominance market share result against the thresholds and context described above.

How to Use

Enter the market share thresholds: EU Commission presumes dominance > 50%, rebuttable below 40–50%; UK CMA uses 40%+ as indicative; US DoJ uses 50%+ for the scenario you are assessing. Assess presumptive market dominance based on market share thresholds: EU Commission presumes dominance > 50% and rebuttable below 40–50%; UK CMA uses 40%+ as indicative; US DoJ uses 50%+. Includes HHI concentration analysis. Use the dominance market share result to inform your calculation.

ICN Dominance Threshold >40% Market Share Calculator

Statute of Limitations

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How to Use

Frequently Asked Questions