You already built this artifact in M8.04, as the output of analysis. Now look at it again as a communication object, because the one-page investment memo is the single most valuable thing you will write in this profession and the purest application of everything from Minto's pyramid to SCQA. Recall the six-part structure: (1) the business · (2) why it's a good business · (3) the variant perception · (4) the three things that must go right · (5) valuation & expected return · (6) sell criteria. Seen through Minto's lens, this is no arbitrary list. It is a pyramid, and its parts map one-to-one onto the five spine questions. The variant perception (part 3) is the governing thought: it is the single claim the whole memo exists to make and defend: here is where my view of the future differs from the price's, and why I might be right. Parts 1–2 are the SCQA setup (the Situation and Complication: what this is and why it's a good business the market already prices highly). Parts 4–5 are the MECE support for the variant claim (the conditions it needs, and what it's worth if they hold). Part 6 is the pre-commitment that makes the whole thing falsifiable. The memo is a pyramid with a variant perception at its apex.
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Why does an investment memo have to fit on one page?
The discipline of the single page is the communication lesson. One page is not a length limit; it is a comprehension guarantee and a thinking test. If your reasoning does not fit on a page, you do not yet have a thesis. You have notes, and the failure to compress is the Feynman signal that the understanding is not finished (see why communication is an analytical skill). The page is also the artifact your future self reads when the position is down 30% and you need to know, fast, whether the thesis is broken or merely unpopular; a rambling five-pager cannot do that job. Every constraint of the form serves comprehension: the header carries the metadata (name, ticker, date, price, data-through, sources) so the memo is auditable and time-stamped; each of the six parts is one tight paragraph answering exactly the question its heading raises (the vertical Q&A); the valuation is a range with a date, never a false-precision point.
What does a good investment memo look like?
The reference exemplar is the Titan one-page thesis from M8.04. Reread it now with the structure in mind and notice what it does as writing: it leads with what the business is and why it's good (setup), states a genuine variant perception (governing thought: the formalization runway is longer than the implied fade), supports it with exactly three falsifiable conditions (MECE support, not ten hedged worries), values it as a range with an explicit "interested below ₹X, watcher above ₹Y," and pre-commits the sell criteria. Every spine question is answerable from the page. There is no throat-clearing, no adjective inflation, no buried lede. That page is the standard, and what follows is the toolkit for producing it and its longer and more visual cousins.
The clearest way to feel the difference the toolkit makes is a before/after: a rambling memo rewritten to standard. That rewrite, worked in full on Costco, is Worked example 1; read it after this section. Its lesson previews everything here. The "before" is not wrong about any fact. It is a comprehension failure, burying a real conclusion under observations, throat-clearing, and a missing variant perception, and the rewrite adds no new analysis, only structure and the "so what" discipline. Same facts, a decision the reader can now actually make.