Comprendre et mesurer la concentration du marché à l'aide de l'indice Herfindahl-Hirschman (HHI)

Understanding and Measuring Market Concentration Using the Herfindahl-Hirschman Index (HHI)

In the complex world of economics, market concentration plays a key role in understanding the competitive dynamics within an industry. One of the most effective tools to measure this is the Herfindahl-Hirschman Index (HHI). But what exactly is HHI, and how can it be calculated? This article will dive into the details, breaking down the concepts in an easy-to-grasp manner.

What is the Herfindahl-Hirschman Index (HHI)?

The Herfindahl-Hirschman Index (HHI) is a widely used measure of market concentration. It helps determine how competitive an industry is by aggregating the market shares of all the firms within that industry. The calculation is straightforward yet powerful, offering a clear picture of whether an industry is a monopoly, oligopoly, or highly competitive market.

How is HHI Calculated?

The HHI is calculated using the formula:

HHI = Sum of the squares of the market shares of all firms in the industry

This means that for each firm in the market, you take its market share, square it, and then sum all these squared values. If all market shares are expressed as percentages, the HHI value will range between 0 to 10,000 points. Here’s a step-by-step breakdown of the calculation in a hypothetical market:

• Firm A has a market share of 10%
• Firm B has a market share of 20%
• Firm C has a market share of 30%
• Firm D has a market share of 40%

The HHI would be calculated as follows:

HHI = (10²) + (20²) + (30²) + (40²) = 100 + 400 + 900 + 1600 = 3000

Interpreting HHI Values

The HHI value helps analysts, economists, and policymakers understand the level of competition within a market. Here’s how to interpret the results:

• HHI < 1,500: The industry is considered to be a competitive marketplace.
• 1,500 ≤ HHI < 2,500: The industry is moderately concentrated.
• HHI ≥ 2,500: The industry is highly concentrated, indicating less competition and possible monopolistic or oligopolistic market structures.

Real-World Example: The Soft Drink Industry

Let’s take a real-world example to make things more tangible: the soft drink industry in the United States. Suppose the market shares are as follows:

• Coca-Cola: 40%
• Pepsi: 35%
• Dr Pepper: 15%
• Smaller brands: 10%

We calculate the HHI as:

HHI = (40²) + (35²) + (15²) + (10²) = 1600 + 1225 + 225 + 100 = 3150

An HHI of 3150 indicates that the soft drink industry is highly concentrated, suggesting limited competition.

Key Inputs and Outputs

Inputs

• Market Shares: Percentages representing the share of the market controlled by each firm. These values should be between 0% and 100%.

Outputs

• HHI Value: A numerical value typically ranging from 0 to 10,000 that indicates the level of market concentration.

Why is HHI Important?

Understanding the HHI of a market is crucial for several reasons:

• Policy Decisions: Governments and regulatory bodies use HHI to evaluate whether mergers and acquisitions will harm competition within an industry.
• Market Analysis: Companies use HHI to gauge the competitive landscape, helping them strategize their market entry or expansion plans.
• Economic Health: Economists look at HHI to assess market health and competition levels, which are pivotal for a healthy, functioning economy.

FAQs

What happens if market shares are not expressed as percentages?

Market shares should be converted to percentages before calculating HHI to ensure accuracy. For instance, if a firm's market share is 0.5 (out of a total of 1), it should be converted to 50%.

Can HHI be used for global market analysis?

Yes, HHI can be applied to any defined market, whether it’s local, national, or global, as long as the relevant market shares are available.

Is there a threshold for when HHI becomes concerning?

Regulatory bodies like the U.S. Department of Justice consider an HHI above 2,500 to indicate high concentration, which may warrant scrutiny, especially in cases of mergers and acquisitions.

Summary

The Herfindahl-Hirschman Index is an invaluable tool in the world of economics, providing a clear metric for assessing market concentration. Whether you're a policy maker, an economist, or a business strategist, understanding and utilizing HHI can offer invaluable insights into market dynamics, helping you make informed decisions.

Tags: Économie, Analyse de marché, Finance