Conducting Investment Postmortem

Conducting Investment Post-Mortem

When to use this skill

• After a thesis outcome materially diverges from expectations.
• After large drawdowns, unexpected underperformance, or forced exits.
• When the user asks to capture lessons and upgrade investment process.

Workflow

1. Plan

• Define case boundary: entry thesis, holding period, expected milestones, actual outcomes.
• Define post-mortem questions before judging results.

2. Validate

• Reconstruct decision context using only time-consistent information.
• Separate process error from outcome variance.
• Verify attribution across thesis, macro, valuation, and execution.

3. Execute

• Produce root-cause analysis with evidence.
• Map each root cause to process-level guardrails.
• Update policy proposals for future decisions.

Instructions

• Do not judge solely by PnL outcome; evaluate decision quality.
• Distinguish:
  • Thesis error
  • Valuation error
  • Macro regime mismatch
  • Position sizing/risk management error
  • Execution discipline error
• Convert lessons into concrete rule updates, not generic advice.

Post-mortem checklist

• Original thesis and assumptions reconstructed
• Outcome vs expectation gap quantified
• Root causes categorized
• Process changes proposed
• Monitoring triggers updated

Output template

## Investment Post-Mortem: <Case>

### Expected vs Actual
- Expected: <...>
- Actual: <...>
- Gap: <...>

### Root Cause Analysis
1. Thesis error: <...>
2. Valuation error: <...>
3. Risk management error: <...>

### Process Upgrades
- New pre-entry check: <...>
- New sizing rule: <...>
- New invalidation trigger: <...>

### Forward Protocol
- What will be done differently next time: <...>

Error handling

• If historical decision context is incomplete, explicitly mark unknowns.
• If attribution is ambiguous, present ranked hypotheses with confidence levels.
• If proposed rule changes conflict with long-term policy, escalate and resolve policy first.

Resources

• managing-long-term-investment-policy
• reviewing-financial-analysis
• analyzing-macro-regime
• attributing-portfolio-performance（協同技能：系統性績效歸因作為 postmortem 的量化輸入）
• sizing-portfolio-positions（協同技能：檢討倉位規模是否為虧損主因）