Shared suppliers: trace a common operating bottleneck
Two holdings in different industries can depend on the same production node. A shared supplier map asks which products require that node, what substitutes exist and when a disruption could reach each company. It is an operating-dependency exercise, not a calculation of share-price correlation.
Establish the specific supplier relationship
TSMC’s annual report describes its foundry business and operating context. A supplier’s report can explain capacity and process categories, but it does not independently prove that every company in a broad technology theme is a customer. Customer relationships need issuer disclosures, contracts or other direct first-party evidence.
Record the supplied item, manufacturing site or process where known, affected product, and evidence strength. A statement that a company “uses semiconductors” is too broad to establish dependence on one foundry. Likewise, sharing a supplier name does not prove that the same factory or constrained process is involved.
Hypothetical bottleneck map
Assume fictional Holdings North and South both require a specialized controller from Supplier Stone. North uses it in Product N, representing 40% of its revenue; South uses it in Product S, representing 15%. The portfolio holds 10% in North and 8% in South.
An editorial exposure-coverage proxy is 10% × 40% + 8% × 15% = 5.2% of portfolio weight linked to those product populations. It is not a forecast of loss: a shortage can affect timing, inventory and substitutions differently.
| Dependency worksheet | North | South |
|---|---|---|
| Verified input | Controller C | Controller C |
| Product population | Product N | Product S |
| Revenue share of population | 40% | 15% |
| Usable inventory buffer | Four weeks assumed | Twelve weeks assumed |
| Alternative qualification | Six months assumed | Not publicly known |
| Next operating checkpoint | Buffer exhaustion | Alternate supply evidence |
All quantities and relationships in this example are hypothetical. The exposure multiplication is a research convention, not an official supplier-risk metric. Do not fill unknown revenue shares with an industry average and present the result as a company fact.
Add time and substitutability
A four-week inventory buffer and a six-month qualification period imply a different investigation priority from a twelve-week buffer with a qualified second source. Inspect whether inventory is the exact usable component, not simply total inventory on the balance sheet. Finished goods, obsolete stock and unrelated parts cannot all serve as that buffer.
Ask whether a substitute is technically qualified, commercially available and accessible in the needed volume. A supplier announcing a new product does not establish that the customer can use it immediately. Conversely, an internal redesign may reduce dependence before the public supplier list changes.
Follow one event through distinct channels
If Supplier Stone reports a production interruption, create one event and link it to both product populations. Do not count the same news twice as independent confirmation. For North, inspect delivery schedules near the four-week point; for South, inspect whether its longer buffer remains usable and whether demand has changed.
Also watch for second-order effects. A customer may postpone orders from several other suppliers if one missing component blocks assembly. Those indirect links need their own evidence and should be labeled inferred until confirmed. A broad supply-chain diagram can otherwise become a collection of untested arrows.
Update the map after product redesigns, acquisitions or supplier qualification changes. The useful output is a list of verified nodes, affected business populations, buffer clocks and unresolved substitutions. It does not prescribe a portfolio allocation or estimate losses from a disruption whose duration remains unknown.
FAQ
Does a common supplier mean identical risk for both holdings?
No. Products, sites, inventory and substitution paths can differ substantially even when the supplier name matches.
Can total inventory divided by sales estimate the component buffer?
Not reliably. The relevant numerator is usable stock of the specific constrained input, with a compatible consumption rate.