Bull-Bear Written Synthesis
Write both sides of a market thesis before risking capital
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 6
- Confidence
- 96%
The method turns writing into a decision-quality tool. Before acting, articulate the strongest bull and bear cases rather than treating conviction as certainty. Compare the evidence, locate the unresolved friction between the two views, and translate that uncertainty into position size and sequencing. Recording the reasoning forces assumptions into the open and creates an audit trail against which later decisions can be judged. The goal is not to predict perfectly; it is to understand what must happen for each case to prevail, recognize when the evidence changes, and avoid rewriting the original thesis after the outcome is known. Repeated use improves both market education and personal accountability.
Origin
Todd Harrison developed the practice through his real-time Trading Diary at TheStreet, where writing helped him synthesize and sequence his market thinking.
Core principles
- 01Every market thesis has a credible opposing case
- 02Writing exposes gaps and sequences reasoning
- 03Friction between opposing views produces insight
- 04A recorded thesis creates accountability
How to run it
- 1
State the decision
Define the security, time horizon, proposed action, and evidence currently available. Make the decision narrow enough to evaluate later.
Pro tip Write the question before researching further so the analysis does not drift.
Watch out Do not begin with a desired conclusion and work backward.
- 2
Build the bull case
List the strongest mechanisms that could create upside, including catalysts, valuation support, and favorable structural changes.
Pro tip Write the case as if you had to persuade a skeptical investor.
Watch out Do not rely solely on price momentum or enthusiasm.
- 3
Build the bear case
List the strongest mechanisms that could invalidate the thesis or create permanent loss. Include adverse evidence even when it conflicts with your position.
Pro tip Ask what a well-informed short seller would emphasize.
Watch out A token bear case defeats the purpose of the exercise.
- 4
Locate the friction
Identify the assumptions on which the two cases diverge and specify what observable evidence would resolve them.
Pro tip Prioritize disagreements that can be monitored over vague macro concerns.
Watch out Do not mistake an untestable narrative for a decision rule.
- 5
Sequence the position
Choose whether to enter, wait, scale, hedge, or decline based on the evidence and uncertainty. Match exposure to conviction rather than presenting the thesis as binary.
Pro tip Use staged entries when the thesis is promising but key evidence remains unresolved.
Watch out Do not let detailed analysis justify an oversized position.
- 6
Review against the record
Revisit the written cases when material evidence changes and compare the outcome with the original reasoning. Update the position without rewriting history.
Pro tip Separate a good process with a bad outcome from a bad process with a lucky outcome.
Watch out Avoid judging decision quality solely by profit or loss.
In the wild
An investor writes that regulatory approval, strong clinical data, and institutional adoption support the bull case. The bear case highlights cash burn, uncertain reimbursement, and a crowded patent landscape. Because approval is unresolved, the investor opens a small position and identifies the regulator's decision and funding runway as review triggers.
→ The investor gains exposure while containing the cost of being wrong and preserving room to scale.
Common mistakes
Writing a straw-man bear case
Listing only weak objections reinforces the preferred thesis rather than testing it. The opposing case must be credible enough to change the decision.
Confusing detail with conviction
A long analysis can still rest on uncertain assumptions. Position size should reflect the quality of evidence, not the number of words written.
Rewriting the thesis afterward
Changing the original rationale after the outcome destroys accountability. Preserve the initial record and append updates separately.
Is it for you?
Best for
Investors and traders making uncertain decisions where credible evidence supports both upside and downside.
Not ideal for
It is not ideal for mechanical strategies whose entry, sizing, and exit rules are already fully specified.
From the transcript
“there's always a bear case and there's always a bowl case.”
“that friction between those opinions is where both education is found, but it's also where profitability lies”
“it allowed me an opportunity to uh synthesize my thoughts and really lay it out there in a way that held me accountable to really…”
From the episode
Todd Harrison Discusses Biopharmaceutical Investments
Todd Harrison