Essay · 2026
The Investor's Substrate Test
Score the substrate beneath any single position in seven minutes. A 5-axis profile and a 0-10 score for any holding. Free.
You can be right about the company and wrong about the position.
Most theses get scored. The substrate underneath the thesis rarely does. That gap is where good judgement quietly turns into mediocre returns: the company performs, the position doesn’t, and the post-mortem cannot name what was missing because the thing that was missing was never written down.
The Investor’s Substrate Test is a 7-minute, 5-axis tool for scoring the substrate beneath any single holding. You score the position before the news, not after it. Five axes carry the score: durability, asymmetry, replicability, couplings, and optionality. Each contributes 0 to 2, summing to a 0-10 score plus a one-page profile defensible to a partner, an LP, or future-you.
When to run it.
Before sizing a new position. The score becomes part of the position memo and gets re-scored every six months for as long as the position is held.
Quarterly on existing positions. A score that drifts down two points in two quarters is the signal that the substrate is eroding while the thesis still looks intact. That is the highest-leverage early warning available to a long-only allocator.
What a good score looks like.
The 0-10 band reads in three regions. Below 4 is a canopy bet: the position depends on the thesis playing out, with little behind it if it doesn’t. 4 to 7 is mixed, usually mispriced one way or the other. Above 7 is a substrate bet: the position holds even when the thesis turns out to be partially wrong, which is the actual claim worth making.
The numbers matter less than the forcing function. If you cannot name the substrate in one sentence, the score is not the problem. The thinking is.
Download.
The test is a single PDF. Score one position in seven minutes. Score a portfolio in an afternoon.
The Investor’s Substrate Test
156KB ∙ PDF file
The Investor’s Substrate Test is a companion to The Forest Floor Is the Product, the article that develops the substrate-vs-canopy distinction across knowledge work, software, ecosystems, and capital allocation. If a term in the test is doing more work than it explains, The Lens Lexicon (also free) defines the ten terms that carry the framework.
What is the substrate sentence under your largest position?
If a single argument here changed what you were about to trust, the highest-leverage move is to subscribe on Substack. One piece a week, no filler.