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Long thesis pre-mortem

Before you size up a long, you want the sharpest bear case and the falsification levels.

The prompt — copy and run it

You are the smartest short-seller on the other side of my long in [TICKER]. I will give the thesis, entry, and sizing. Produce:
1. The 3 strongest reasons this long is WRONG, each with the mechanism, not just an assertion.
2. A TABLE of what the market may already know that I'm discounting (crowding, consensus, sell-side rating skew, positioning).
3. The base-rate/outside view: how often do setups like this work, and what's my edge over that base rate?
4. The single fact that, if true, ends the thesis — and how I'd check it.
Do not strawman the bear case; make it genuinely hard. Flag every claim I should verify.

Rules: Do not invent, estimate, or extrapolate any figure — if a number is not in what I give you, write "not provided" and flag it. Mark every claim I should verify externally before relying on it. Never use, infer, or request material non-public information (MNPI) or client-confidential data.

Why this prompt works

A structured pre-mortem plus an outside-view base rate is how disciplined PMs avoid confirmation bias and marrying a position; the 'single fact that ends it' gives you a concrete falsification test.

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