The Circle of Competence
Arche treats the circle of competence as a boundary, not a trophy. An analyst does not need expertise in every company, or even many; the requirement is to evaluate selected businesses correctly and know where that ability ends.
Investing rewards accuracy, not coverage. A person who deeply understands regional banks and nothing else has everything they need — provided they never wander. The catastrophes come not from small circles but from uncharted borders: the moment a confident opinion outruns actual understanding.
The one-paragraph test
Arche’s first filter is blunt: do we understand it? A practical proxy: can you explain, in one paragraph and no jargon, how this company turns its product into cash — and what would have to go wrong for the cash to stop? If the paragraph will not write, the problem usually is not the writer.
When filing evidence supports it, a company page may include a revenue-to-profit flow showing how reported statement lines fit together. Other pages explicitly say that the flow is unavailable. Its presence or absence describes evidence coverage, not whether a reader understands the business; the one-paragraph test remains the reader’s responsibility.
The too-hard pile is a triumph, not a failure
Many businesses deserve a pass: pharmaceutical pipelines, unfamiliar technologies, and companies whose economics hinge on a single regulatory or scientific coin flip. The point is not that those businesses are bad; it is that their outcomes are not knowable by this particular analyst. Unknowable plus confident is an expensive combination.
This site does not assign a Too Hard flag in its current company facts. The reader must make that boundary explicit. Limited history, missing filing lines, unfamiliar economics, or dependence on a binary event are reasons to abstain from a conclusion, not claims that the company is bad. The boundary is personal and can move, but only through real understanding — never through price action or popularity.
Working your own circle
- Inventory what you actually know. Industries you’ve worked in, products you’ve bought for a decade, business models you can explain to a teenager.
- Stay home more than feels natural. The market never penalizes a pass; it only punishes swings taken outside the zone.
- Expand deliberately. Read filings until a new industry’s one-paragraph explanation writes itself — that’s the border moving, legitimately.
Everything else on this site assumes this essay. The published facts can inform an analysis; only you can measure whether you understand the business.