A step-by-step guide to mapping supplier and buyer relationships for any public company using SEC filings, deal announcements, and financial data.
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Every public company is embedded in a web of suppliers and customers. Mapping these relationships transforms how you evaluate a stock — revealing concentration risks, growth catalysts, and vulnerabilities that balance sheets alone can't show. These relationships also connect to broader product categories, industries, and macro trends that shape how value flows through the economy.
When you buy a stock, you're not just buying one company. You're buying into its entire supply chain. If a key supplier fails, your company suffers. If a major customer cuts orders, revenue drops. Understanding these connections is fundamental to sound investment analysis.
The richest source of supply chain data is the SEC itself. Companies are required to disclose material relationships in their annual filings.
Look for the "Customers" or "Major Customers" section. Companies must disclose any customer representing 10% or more of total revenue. This requirement under ASC 280 creates a reliable, standardized dataset.
For example, Qualcomm's 10-K reveals that Apple consistently represents over 20% of their revenue. That single data point tells you that Qualcomm's fortunes are meaningfully tied to Apple's iPhone sales.
Quarterly filings provide more recent data, though with less detail. They're useful for tracking changes in customer concentration over time.
Management often discusses supply chain strategy in earnings calls — new supplier agreements, supply diversification efforts, and logistics challenges. These qualitative signals complement the quantitative data in filings.
Contract announcements are gold for supply chain mapping. When TSMC announces a $40 billion investment in Arizona fabrication facilities, or when Samsung signs a multi-year OLED supply agreement with Apple, these deals reveal both the direction and magnitude of supply chain relationships.
Track these data points for each deal:
Once you've collected supplier-buyer pairs, organize them as a directed graph:
For Apple's supply chain, this might look like:
Each arrow in this graph represents a revenue dependency. The thickness of the arrow represents how much revenue flows through that relationship.
For each relationship, calculate exposure metrics:
What percentage of a supplier's revenue comes from a specific customer? A supplier deriving 50% of revenue from one buyer is highly vulnerable to that relationship.
How diversified is a company's customer base? A Herfindahl-Hirschman Index (HHI) across customers tells you whether revenue is spread across many buyers or concentrated in a few.
How many tiers deep does the supply chain go? A disruption at tier-3 (a supplier's supplier's supplier) can cascade through the chain. The deeper you map, the more risks you uncover.
A supply chain is only as strong as its weakest link. For each major supplier and customer, track:
A supplier with declining margins and rising debt may be unable to invest in capacity or quality, creating downstream risk for all its customers.
Some suppliers are irreplaceable. ASML is the only manufacturer of extreme ultraviolet (EUV) lithography machines. TSMC manufactures over 90% of the world's most advanced chips. These chokepoints create systemic risk — and systemic opportunity for the companies that control them.
Look for:
Manual supply chain mapping works for one or two companies, but scaling it across a portfolio requires automation. Modern supply chain intelligence platforms:
Macroplane does all of this starting from a single ticker input. Search any public company and get its full supply chain map, relationship strength indicators, and financial health metrics across the entire network. From there, you can explore the product categories a company participates in, or build an investment thesis around the supply chain patterns you discover.
Start with your largest holding. Look up its 10-K filing. Identify the top three suppliers and top three customers. For each of those six companies, check their financial health. Are any showing signs of stress?
This simple exercise often reveals risks and opportunities that weren't visible from looking at your holding in isolation. That's the power of supply chain mapping — it turns single-company analysis into network analysis, and network analysis is where the real edge lies.