Customer concentration is the only risk in this atlas with a clean base rate, a live natural experiment, and a survivor's blueprint all in the public record. It is also the one every private company in the sector is currently running hotter than the company that died of it.
Any single customer above ~15% of revenue should be modelled as a binary event, not a growth line. Above 25%, you are a division of that customer with a different cap table. Concentration risk is not linear in the percentage. It is a cliff, and the cliff moves closer when your buyers compete with each other.
The base rate: Appen
Appen is the only company in this space that has run the full cycle in public, and the shape of it should be printed on the wall of every board meeting in the sector.
| Figure | |
|---|---|
| Peak market cap, August 2020 | US$4.3B |
| Revenue concentration at peak | 80% from five clients — Microsoft, Apple, Meta, Google, Amazon |
| Google contract terminated, 22 Jan 2024 | ~US$83M, roughly a third of remaining revenue |
| Share price reaction, same day | –40% to –41% |
| Revenue, FY2021 → FY2025 (USD) | $447.3M → $388.3M → $273.8M → $235.2M → $232.7M |
| Drawdown from peak | 97% |
| Market cap, 28 Aug 2026 | A$330M |
Sources: The Verge's December 2025 feature for the peak and the 97% drawdown; stockanalysis.com for the revenue series and current market cap; NBC for the Alphabet termination. Note the currency bases differ — the revenue series is USD, the market cap AUD. Never mix the two series.
The lesson is not that Appen executed badly. FY2025 was a decent year: operating revenue $230.8M, underlying EBITDA up 250% to $12.2M, gross margin 40.3% — a better gross margin than Mercor runs today. The collapse was caused by buyer concentration meeting a change in training technique. And Appen's top five are still 74.3% of revenue, up from 67.3%. Concentration does not necessarily fall as you shrink; it can rise.
One layer down the same supply chain, Sama issued redundancy notices to 1,108 employees at its Nairobi delivery centre in April 2026 after Meta terminated a single content and annotation contract (TechCabal). One buyer decision, a thousand jobs, weeks.
Where the current cohort sits
The private set is running the same exposure, and in several cases worse.
| Company | Concentration | Source |
|---|---|---|
| Mercor | ~91% of H1 2026 revenue from AI foundation-model companies, OpenAI and Anthropic dominant | The Information, via BigGo |
| TaskUs | top 10 = 58%, top 20 = 71%, Meta alone 26% (up from 22%) | TaskUs FY2025 10-K |
| Innodata | largest customer 37% of Q2 2026 (from 56% in Q1), second 34%, top two 71% | StockTitan |
| Appen | top five 74.3% | Appen AR2025 |
| Concentrix | five largest ≈ 19%, 2,000+ clients | Concentrix FY2025 10-K |
| GLG | top ten 19.0%, no client above 6%, 90% of revenue recurring | GLG S-1, Oct 2021 |
Mercor's founder, Brendan Foody, has publicly compared the company's concentration to Nvidia's — four customers at 61% of revenue — as a defence of it [WEAK — the comparison appears in the research record without a retrievable primary link]. It is a revealing analogy. Nvidia's four customers each need Nvidia more than Nvidia needs any one of them, and Nvidia has no substitute. A data vendor at 91% has neither condition.
The GLG "no client above 6%" figure is cited to the October 2021 S-1 in one research file and flagged as unsourced in the contradictions register, which also records the S-1 as unread. The 19.0% top-ten figure and the 90%-recurring figure come from the same document. Treat the 6% as directionally right and worth verifying against the filing before it is quoted anywhere consequential.
Neutrality is the product
The sharpest fact in this atlas is that Meta's $14.3B was simultaneously the largest financing and the largest customer-loss event in the category's history.
On 12 June 2025 Meta bought a 49% non-voting stake in Scale AI at a ~$29B valuation and took founder-CEO Alexandr Wang to run its superintelligence effort (NYT; Wikipedia reports the figure as $14.8B — the two circulate interchangeably). What followed, within weeks: Google cut ties, having spent ~$150M with Scale in 2024 with ~$200M planned for 2025; OpenAI departed; Microsoft pulled back; xAI began exploring alternatives (Sacra; Computerworld). In July 2025 Scale cut 200 FTEs (~14%) and roughly 500 contractor relationships.
Then the punchline. By August 2025, Meta's own researchers reportedly rated Scale's data low quality, and Meta itself was routing work to Surge AI and Mercor (TechCrunch). The buyer that destroyed the vendor's neutrality did not even end up consuming the output it had paid $14.3B for a claim on.
If your buyers compete with each other, neutrality is the product. Anything that compromises it — equity, exclusivity, a shared executive, a board seat — destroys revenue outside that buyer faster than it grows revenue inside it. This is why Google's approach to Mechanize was reportedly structured as a technology licence plus hiring select staff at $1.5B+, not an acquisition (TNW). The structure is the lesson.
What the survivors did differently
Set the two spread books beside each other. GLG: top ten at 19.0%, no client above 6%, 90% of revenue on subscription, 22 of the top 25 clients retained for over a decade, 2,700+ clients, segment contribution margin above 70%. Concentrix: five largest at 19%, 2,000+ clients, 160+ Fortune Global 500 brands, largest-client relationships averaging 16 years.
Neither of those is an accident of growth. They are policies. Six things separate them from the casualty list:
- Contract structure over transaction structure. GLG converted a per-call spot business into account-level subscriptions. That turns revenue visibility from a weakness into a strength — the same move ADP made in payroll.
- Deliberate buyer fragmentation as a rule, not an outcome. "No client above 6%" is a decision you make while turning down revenue.
- Multi-year embedded relationships instead of project wins. Sixteen-year averages are not sold, they are installed.
- Never take equity or strategic investment from one buyer in a competitive buyer set.
- Sell into a function, not a project. Functions have budgets that renew; projects have budgets that end.
- Own the compliance obligation. GLG's chaperoning, ADP's payroll-tax liability. This is the only moat in the whole model that gets stronger as the buyer gets more sophisticated — see Getting cut out.
And the honest coda: diversification prevents the cliff, it does not create a multiple. Concentrix trades at 0.70x EV/revenue with a $1.32B net loss. GLG carried $959.9M of debt into an IPO it withdrew in March 2022. GLG is the best-designed version of this business anyone has built and it still could not get out at a good price. Spread your book because the alternative is Appen, not because it will re-rate you.
The in-housing clock
Concentration and in-housing are the same risk viewed from two ends. The trigger is predictable: a buyer in-houses when your function becomes (a) large enough to matter in their P&L, (b) strategic enough to be a differentiator, and (c) legible enough to hire for. All three are already true at the commodity end of Expert data for frontier labs — OpenAI hired 100+ ex-bankers directly, xAI cut 500 generalists to build a specialist team in-house. Track the three conditions per customer. When all three go true, the clock has started, and the only question left is whether your book is wide enough to survive it.