Find Shared Suppliers Across a Portfolio and Weight the Exposure

Key findings

• Shin-Etsu appears upstream of TSMC, Samsung, Intel and Micron in the published Altsets examples.
• The displayed Shin-Etsu cost shares sum numerically to 3.90 percentage points across four separate company cost bases, giving a 0.975% cost-share indicator for an equal-weight illustrative basket.
• Common supplier identity does not establish common facilities or products; lithography, process control and materials vendors are not substitutes merely because they share customers.

To find shared suppliers across a portfolio, map each holding to its upstream counterparties, normalize supplier identities and group the resulting supplier-to-customer edges by supplier. Then retain the holding weights and customer cost shares. Counting repeated names identifies overlap; it does not establish how evenly that exposure is distributed or whether the holdings use the same product or facility.

The published Altsets examples show Shin-Etsu Chemical supplying TSMC, Samsung Electronics, Intel and Micron. The displayed customer cost shares are 1.33%, 0.29%, 0.94% and 1.34%, respectively. An illustrative equal-weight basket produces a portfolio-weighted cost-share indicator of 0.975%, with TSMC and Micron contributing approximately 68.46% of that indicator. A binary "four holdings share Shin-Etsu" result hides that unevenness.

Those observations come from illustrative source snapshots, not a newly synchronized account dataset. An actual screen needs one analysis date and the investor's own weights. Even then, the output measures shared company-level procurement, rather than expected portfolio loss. The next question is whether a proposed input-price or delivery event affects products used by the connected holdings. The relationship data supplies the candidate routes and their estimated financial weights; product and facility evidence decides which routes belong in the event analysis.

Group upstream edges by supplier, without reversing the denominator

The source examples are the TSMC upstream analysis, Japan semiconductor supplier analysis and Micron supplier map. Each percentage uses the named customer's cost base. It does not measure that customer's share of Shin-Etsu revenue.

The sum is numerically 3.90 percentage points across four separate company cost bases. Dividing by four gives the 0.975% equal-weight indicator. It is a weighted comparison of company procurement shares, not a pooled purchasing total or a proportion of the investor's own expenses. TSMC and Micron account for about 68.46% of the indicator because their two displayed cost shares dominate this particular four-company set.

Make the screening output reveal its coverage

Resolve holdings to economic companies before expanding upstream, so two listings of the same business do not count as two independent customer companies. Use a consistent snapshot date, collect the available supplier edges and normalize aliases before grouping repeated counterparties. For every recurring supplier, retain the linked holdings, measured cost shares and unquantified edges.

Report both breadth and weighted exposure. Breadth answers how many holdings connect to the supplier. The weighted indicator answers how the available company cost shares interact with account allocations. Missing metrics should remain unknown rather than being put at the bottom of a ranking as zeros. A partially quantified supplier may deserve investigation even when a fully quantified supplier has a larger measured indicator.

The example here illustrates that output logic without claiming the displayed snapshots are synchronized. A current account result requires new dated inputs; a historical account result requires the information set accepted at that historical decision.

Shared procurement does not establish a common physical failure point

The Shin-Etsu name repeats across four holdings, but the edges alone do not identify identical materials, plants, logistics routes or qualification requirements. If an event concerns one product or facility, the screen should admit only the routes supported by relevant evidence. Without it, label the finding shared company-level procurement.

This matters for substitution too. Micron also connects to ASML, Lam Research, Applied Materials and KLA. Those vendors widen its supplier list, but different equipment functions do not replace Shin-Etsu materials. A list of several supplier names is not evidence of several qualified sources for the same input. The replacement-supplier guide explains how to screen alternatives against the affected input function.

Test a procurement event against the right holdings

A testable hypothesis is that an unexpected Shin-Etsu input-price or delivery change has a larger effect on customers with greater pre-event cost exposure to the affected materials. That requires product matching and controls for the semiconductor cycle. A connected company buying an unaffected product can provide a useful comparison, despite sharing the same corporate supplier.

The cost-share indicator helps prioritize those observations; it does not specify the size of a production interruption. Price sensitivity and operational continuity need different bridges.

Keep this screen distinct from shared-customer analysis. Customers shared by owned suppliers create a demand question; suppliers shared by owned customers create a procurement question. Preserving that direction is what turns repeated names into useful portfolio research. Altsets methodology defines the metrics and missing-value treatment.

Sources

• Altsets supply chain dataset
• Micron fiscal Q2 2026 filing
• ASML annual report

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Methodology

Read the methodology for this research.

Cite this research

Altsets Research. "Find Shared Suppliers Across a Portfolio and Weight the Exposure." Published August 11, 2026. https://www.altsets.com/research/find-shared-suppliers-across-portfolio

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