Investment Memo Style Guide

Rules the memo must follow. These mirror buyside writing conventions and avoid the tells that mark a document as AI-generated.

Voice

• First person plural ("we believe", "our base case") — that's how a buyside team writes.
• Direct, not hedging. "Margins compress 200bps in '27" beats "margins could potentially face some pressure in 2027".
• Confidence calibrated by evidence. State the view, then state the evidence. Hedge once with a "wrong if" — not in every sentence.
• One sentence per idea in narrative sections. Long sentences with comma chains and parentheticals signal AI drift.

Banned vocabulary

Never use these words. They are AI-generated tells:

• "delve", "delves", "delving"
• "leverage" as a verb ("we leverage X to do Y")
• "robust", "comprehensive", "holistic", "seamless"
• "navigate the landscape", "navigate the challenges"
• "in today's fast-paced", "in an ever-evolving"
• "stands out", "sets itself apart"
• "deep dive", "unpack", "double-click"
• "moreover", "furthermore", "additionally" (use a new sentence)
• "It's worth noting that" (just say the thing)

Banned constructions

• Tricolons — three-item lists for rhythmic effect ("fast, scalable, and reliable"). One AI tell.
• Em dash abuse — at most one em dash per paragraph. Prefer periods or commas.
• "Not just X but Y" — overused contrast structure.
• Generic closing summaries — "In conclusion, this is a compelling opportunity that..." Don't write these. End on a specific claim or a tripwire.
• Hedge stacking — "could potentially possibly maybe". Pick one or zero.

Numbers

• Quantify everything. "Margins expanded 380bps" not "margins improved meaningfully".
• Percentages with explicit base. "Revenue grew 28% YoY" not "revenue saw strong growth".
• Multiples in line. "Trading at 18x FY26 EPS" not "trading at attractive multiples".
• Don't invent numbers. If you don't have it from a tool call, write "not disclosed" or omit the line. Never fabricate consensus figures.

Thesis bullet format

Every thesis bullet must be a complete falsifiable claim:

[Specific claim with a number] — [Evidence with a specific number, ideally citing the data point]. Wrong if [specific observable would happen].

Good:

Ad-tier reaches 15% of subs by '27 — Q1 disclosed 40M ad-tier subs (+85% YoY) on a 270M base; trajectory implies 15% mix at constant adds. Wrong if ad-tier ARPU compresses below $8 due to inventory glut.

Bad (vague claim, no falsifier):

Strong product-market fit in ad tier — Management has emphasized this is a key growth area going forward.

Bear case requirements

The bear paragraph is the highest-stakes paragraph in the memo. Rules:

1. Steelmanned. Written as if you actually believed it. If you can't, you don't understand the trade.
2. Specific competitor / customer / regulator named. Not "competition intensifies" — name the company and the product.
3. Coherent world, not a list. The bear case is a story where the thesis is wrong. Connect the dots.
4. Read the bull paragraph and the bear paragraph back to back. If bear reads weaker, rewrite. This is the single most common failure mode.

Tripwires

Every risk row in the risks table must have a tripwire. A tripwire is an observable data point that would invalidate the thesis within the holding period.

Good tripwires:

• "Q3 ad-tier ARPU prints below $8"
• "Top customer announces in-sourcing on Q2 call"
• "Gross margin contracts more than 150bps in any quarter"
• "Insider sales exceed $50M in any rolling 90-day window"

Bad tripwires (not observable / not actionable):

• "Macro deteriorates"
• "Competition increases"
• "Sentiment shifts negatively"

What to pull from filings

When summarizing the business, pull verbatim from the 10-K Item 1 where the company's own language is tighter than rewriting it. Quote with quotes and source: "[exact phrase]" (10-K Item 1).

For risks, prefer pulling from Item 1A and the company's own disclosure language — it's the most defensible risk framing in the memo.

Closing the memo

Memos do not need a "conclusion" section. The header already states the recommendation; the thesis bullets state the view; the scenarios state the math. A closing paragraph that restates these is padding.

The last section in the body is Monitoring KPIs — the specific metrics that confirm or kill the thesis. That's the right note to end on: what to watch.