AI Training Market Concentration

Method and definitions

The public job boards of the AI training platforms this site tracks, read every day. Every figure is computed by one database query over the window shown, the same query for the live report and for every edition. Each figure states its sample beneath it.

HHI

Herfindahl-Hirschman Index: the sum of every platform's squared percentage share of open roles, from near 0 (many small platforms) to 10,000 (one platform). Read with the US merger-guideline thresholds: under 1,500 unconcentrated, 1,500 to 2,500 moderately concentrated, above 2,500 highly concentrated.

Share

A platform's open roles in a kind of work over all open roles in it, on the last day of the window.

Like for like

The change figure counts only platforms already tracked when the window opens, so a platform's arrival in this dataset is not read as a change in competition.

Open role

A role listed by a given day and still in its platform's feed that day.

Kind of work

Each role is classified from its title and description into one of the twelve kinds of AI training work this site tracks, from AI evaluation and coding to multilingual and audio work. Every kind links to its own page.

Coverage

The platforms whose public job boards AITraining.jobs reads in full every day. Each figure states how many were read.

Window

Live: the last 28 complete days, in UTC. Edition: one calendar month, in UTC.

What this data cannot tell you

• Platforms that recruit without a public job board are not counted. Several large ones invite workers to projects directly.
• A listing is not a hire. Some platforms keep evergreen roles open for months, and some post one listing per language or country.
• Shares are of public listings, not of workers hired, hours worked or revenue; a platform posting one role per language or country weighs more here than its hiring may.

How the job feeds are read and roles are classified: site methodology. How fresh, complete and consistent the data is, checked every day: data quality and coverage.

Editions

The live report covers the last 28 complete days and changes every day. Each complete month is also published as an edition, frozen two days after the month ends, so a figure you cite from an edition never moves.

• Live dataLast 28 complete days, recomputed daily
• September 2026 editionFrozen 10 Oct 2026
• August 2026 editionFrozen 10 Oct 2026

Cite and reuse

Free to quote, chart and republish under CC BY 4.0 with a link to this page. This edition is frozen, so its figures will read the same later.

@misc{aitrainingjobs_ai_training_market_concentration_2026_09,
  author = {{AITraining.jobs}},
  title = {AI Training Market Concentration, September 2026 edition},
  year = {2026},
  howpublished = {\url{https://www.aitraining.team/research/ai-training-market-concentration/2026-09}},
}

More research

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• AI Training Platforms ComparedHow do the AI training platforms compare on listings, pay, reach and turnover?Read the report
• The AI Training Jobs IndexIs the market for human AI training work growing, week by week?Read the report
• How Long AI Training Roles Stay OpenHow long do AI training roles stay listed, and which kinds of work turn over fastest?Read the report
• When AI Training Roles Are PostedWhen are AI training roles posted, and when do people apply?Read the report
• Where AI Labs Are Pushing: The Expertise Being Hired, Week by WeekWhich kinds of expertise are AI training platforms hiring more of, week by week?Read the report
• AI Training Vendor HealthWhich AI training platforms are growing, holding or shrinking their hiring, and how are their rates moving?Read the report
• The State of AI Training PayWhat does AI training work pay, by kind of work and by platform?Read the report

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