Who’s Really Paying for Your Stock’s Growth?
Learn how to use AI and company filings to uncover customer concentration, test revenue risk, and verify your findings before investing.
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Your Stock’s Biggest Customer Could Be Its Biggest Risk
Use one AI prompt to uncover a dependency that headline growth numbers can hide.
✍️ Editor’s Note
When I look at a growing company, my first instinct is to ask how quickly its sales are rising.
But another question deserves equal attention:
Who is responsible for those sales - and what happens if they stop buying?
A company can sell an impressive product, report strong growth, and still depend heavily on a handful of customers. That dependency can be easy to overlook when the conversation revolves around earnings beats and exciting technology.
This week, we’re using AI to investigate customer concentration: how much of a company’s business rests on too few buyers.
You’ll leave with one practical research prompt, a way to check its answers, and a better question to ask before getting excited about your next investment.
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🧩 The Risk Behind the Revenue
Imagine two businesses, each generating $1 billion in annual sales.
One serves thousands of customers. The other gets 40% of its revenue from a single buyer.
Their headline revenue is identical. Their exposure to one customer’s decisions is very different.
That large buyer might negotiate lower prices, delay orders, switch suppliers, or bring production in-house. Even if the relationship remains healthy, the buyer’s own budget problems could affect the supplier.
Customer concentration means that a relatively small number of buyers account for a substantial share of revenue.
It isn’t automatically a reason to reject an investment. A major customer can provide scale, credibility, and repeat business.
The research question is whether the benefits come with a dependency you understand - and whether the company has credible ways to manage it.
📂 Where to Look Before Asking AI
Start with the company’s latest annual report, or Form 10-K, and its latest quarterly report, or Form 10-Q.
The SEC identifies the 10-K as a source of information about a company’s business, risks, and financial results. Useful starting points include its Business section, Risk Factors, and financial statements and notes.
Search the documents for phrases such as:
“Major customers”
“Customer concentration”
“Significant customers”
“Percentage of revenue”
“Loss of a customer”
Read the surrounding paragraphs carefully. A disclosure about outstanding receivables describes money owed to the company; it isn’t necessarily a disclosure about that customer’s share of annual sales.
Also check whether the figures describe the entire company, one business segment, or a particular region.
The denominator matters as much as the percentage.
🧮 A Simple Stress Test
Consider this hypothetical example:
A company generates $1 billion in annual revenue. Its largest customer accounts for 40%, or $400 million.
If that customer reduces purchases by 25%, the direct revenue reduction would be:
$400 million × 25% = $100 million
That equals 10% of the company’s original total revenue, assuming all other sales remain unchanged.
This is a scenario, not a prediction. It doesn’t account for replacement customers, pricing changes, contractual protections, or management’s response.
It also doesn’t tell you how much earnings - or the stock price - would change. Profitability depends on costs, margins, and other factors.
What it does provide is a useful starting question:
How well could this business absorb a meaningful reduction in orders from its biggest buyer?
🤖 The AI Research Prompt
Upload the company’s filings to an AI tool that supports document analysis. Include the prior year’s annual report if you want to compare changes over time.
Then use this prompt:
Act as a careful investment research assistant. Analyze only the company filings I provide.
Identify disclosures about customer concentration, major customers, and dependence on significant buyers.
Create a table showing the reporting period, disclosed customer revenue percentages, whether each figure applies to the whole company or a segment, and the document section or page supporting it.
Distinguish revenue concentration from accounts-receivable concentration. Do not infer customer identities or assume unnamed customers are the same across reporting periods.
Explain any disclosed contract protections, purchasing commitments, cancellation rights, or risks of reduced orders. If the documents do not establish these details, say so.
Where comparable data exists, describe whether concentration increased or decreased. Show the calculation and explain any limitations.
Model a hypothetical 25% reduction in purchases by the largest disclosed customer, holding all other revenue constant. Explain why this is not an earnings or stock-price forecast.
Finish with three unanswered research questions. Clearly separate documented facts, calculations, and interpretation. Do not give a buy or sell recommendation.
✅ How to Verify the AI’s Results
Before using the output, perform these checks:
1. Open every cited passage.
Find each percentage in the original filing. Confirm that the AI has attached the correct period and hasn’t mistaken a discussion of receivables for revenue.
2. Check document dates.
A recently downloaded filing may cover an older fiscal year. Review the latest quarterly report for relevant updates.
3. Recalculate the scenario.
Multiply the customer’s revenue share by the assumed purchase reduction. In our example, 40% × 25% equals a 10% reduction in total revenue under the stated assumptions.
4. Inspect comparisons.
Confirm that both periods use the same measurement. Company-wide annual revenue and quarterly segment revenue aren’t directly interchangeable.
5. Treat missing information as unknown.
An unnamed customer remains unnamed. A relationship described as “long-standing” doesn’t establish guaranteed future purchases.
6. Challenge the interpretation.
Does the filing support the AI’s conclusion, or did the tool turn a possibility into a certainty?
The SEC, FINRA, and NASAA warn that AI-generated investment information can be inaccurate, incomplete, or misleading. Verification is part of the research process.
⚖️ What Would Make the Risk More Manageable?
After establishing the numbers, look for evidence that helps explain the relationship.
Questions worth investigating include:
Commitments: Does the filing describe enforceable minimum purchases, or can orders fluctuate?
Switching difficulty: Would replacing the supplier require substantial time, expense, or qualification?
Customer diversity: Is growth coming from additional buyers, or mainly from the existing largest customer?
Financial resilience: What do cash, debt, and operating costs suggest about the company’s ability to withstand a slowdown?
Avoid treating any one answer as decisive.
A large customer relationship may be valuable and durable. It can still deserve close monitoring.
Similarly, a falling concentration percentage doesn’t necessarily mean the business improved. The largest customer’s sales could have declined faster than everyone else’s. Check the underlying revenue figures.
🎯 Your Five-Minute Action
Choose one company you already own or follow.
Locate its latest annual report and search for “major customers” or “customer concentration.”
Write down three things:
What is disclosed? What remains unknown? What would you check next?
If you find a relevant percentage, use the prompt above to organize the evidence—and verify the output before drawing conclusions.
Your goal is to understand how much of the growth story depends on decisions made by a small number of buyers.
🔐 This Week’s Vault Takeaway
Revenue growth tells you how much more a company sold.
Customer concentration helps you investigate how dependent that growth may be on a few relationships.
Use AI to organize the disclosures, then let the original documents support your judgment.
Vaulting Your Wealth Forward,
– T. D. Thompson
AI Investing Vault
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