Registrar Market Concentration: Measuring Retail Channel Monopoly with the HHI Index

While the Internet Corporation for Assigned Names and Numbers (ICANN) lists more than 2,400 accredited registrars, the global retail domain marketplace is heavily concentrated among a small handful of dominant aggregator conglomerates.

To quantify the degree of competition across top-level domains, economists apply the Herfindahl-Hirschman Index (HHI), the established benchmark used by the US Department of Justice and the Federal Trade Commission to evaluate corporate mergers and monopolistic channel power.

How the HHI Index Is Calculated

The HHI is calculated by taking the market share percentage of each competing registrar in a given TLD, squaring that percentage, and summing the results:

• Unconcentrated Market (HHI < 1,500): Highly competitive retail environment with fragmented registrar distribution and robust price competition.
• Moderately Concentrated Market (1,500 <= HHI <= 2,500): Standard commercial distribution dominated by three or four leading retail channels (the historical profile of .com and .net).
• Highly Concentrated Market (HHI > 2,500): Oligopolistic or captive retail environment where one or two firms command the vast majority of active domain volume.

The Risks of Single-Registrar Capture

For emerging generic top-level domains, achieving retail distribution is the primary operational hurdle. Major retail registrars (such as GoDaddy, Namecheap, Tucows, and Hostinger) operate as gatekeepers:

1. Shelf-Space Leverage: Dominant registrars frequently demand six-figure onboarding fees, premium tiered rev-share margins, and mandatory co-op marketing subsidies before featuring a new gTLD in their primary search autocomplete engines.
2. Channel Holdup Risk: In dozens of mid-tier new gTLDs, a single registrar controls more than 50 percent of the active zone. If that registrar decides to raise retail markups, restrict renewal notices, or demote the extension in customer search results, the registry experiences immediate volume paralysis.
3. Wholesale Squeeze: Registries with concentrated distribution lack the bargaining power to resist aggressive discounting demands from dominant retail distributors.

Why Legacy Anchors Maintain Balanced HHI

In contrast, tier-1 legacy extensions maintain resilient, unconcentrated distribution. In .com, while GoDaddy remains the single largest retail registrar with roughly 38 percent market share, the remaining 62 percent is broadly dispersed across thousands of enterprise corporate registrars (CSC, MarkMonitor), international regional leaders (Alibaba Cloud, GMO Internet), and developer favorites (Cloudflare, Porkbun, Dynadot).

This broad dispersion ensures that no single corporate entity can unilaterally disrupt domain availability or dictate contract terms to the registry operator.

As ICANN prepares to launch the 2026 Next Round of new gTLDs, prospective registry applicants must prioritize multi-registrar channel diversification over short-term exclusivity arrangements with individual retail giants.