Define the market before calculating a score
The IEA's 2026 outlook distinguishes mining and refining concentration. A concentration calculation should preserve that stage boundary instead of combining unlike output into one apparently authoritative number.
Decide whether shares describe countries, companies or facilities, and whether the denominator covers the entire relevant market or only your researched sample. A sample-based score can describe the sample, but it cannot be relabelled global concentration without evidence that the missing market is immaterial.
IEA: Global Critical Minerals Outlook 2026, executive summary ↗
Use HHI as a concentration description
The Herfindahl-Hirschman Index sums squared shares. On a percentage-share basis it ranges up to 10,000; using shares from zero to one gives a maximum of one. State the convention. Do not mix the two scales or apply a legal threshold without the relevant market and legal analysis.
Common ownership and shared processing can change the interpretation. Several facilities may represent one corporate decision centre, while separate companies may rely on one converter. Calculate the measure appropriate to the question, then inspect the network for dependencies that the chosen grouping does not capture.
A worked hypothetical comparison
Two equal suppliers have an HHI of 50 squared plus 50 squared, or 5,000. Four equal suppliers have 4 multiplied by 25 squared, or 2,500. The second is less concentrated on that definition. If all four depend on one processor, however, the lower supplier score does not establish four independent production routes or a lower outage probability.
Choose the right concentration boundary
| Grouping | What it can miss |
|---|---|
| Country | Shared companies or critical individual sites |
| Company | Shared upstream converters |
| Facility | Common ownership and correlated infrastructure |
Your review checklist
- Define product, stage and year.
- State whether coverage is global or sampled.
- Label the HHI scale.
- Investigate shared dependencies after calculating shares.
Investigate with Oreline
Oreline combines concentration context with facility and relationship research. Use the network to test whether a diversified-looking list still shares an upstream dependency, rather than relying on a summary score alone.
Follow the evidence through the supply chain.
Explore Oreline’s guided investigations. No account required.
Explore the sandbox →Frequently asked questions
Does a high HHI predict an outage?
No. It describes concentration under the chosen definition, not the probability or timing of a disruption.
Can unknown output be treated as zero?
No. Keep missing quantities explicit and explain how they limit the denominator and interpretation.