Most investors start with upside. "How much can I make?" is the first question they ask. I've learned to invert this entirely.
Start With the Downside
Before I look at any potential return, I ask three questions:
- What's my maximum realistic loss?
- How permanent is that loss likely to be?
- Can I survive that loss and continue investing?
Only after satisfying myself on these questions do I consider the upside.
Why This Works
The math of losses is unforgiving. A 50% loss requires a 100% gain just to break even. A 75% loss requires a 300% gain. The asymmetry is brutal.
More importantly, large losses destroy your psychological capital. After a devastating loss, investors become either paralyzed (missing the recovery) or desperate (taking excessive risks to recover quickly). Both responses compound the original mistake.
The Framework in Practice
For any investment, I create a simple matrix:
| Scenario | Probability | Outcome |
|----------|-------------|---------|
| Base case | 60% | What happens if things go as expected |
| Bull case | 20% | What happens if things go better than expected |
| Bear case | 15% | What happens if things go wrong |
| Catastrophe | 5% | What happens if things go very wrong |
I then ensure that even the catastrophe scenario doesn't impair my ability to continue investing. This usually means position sizing more than investment selection.
Position Sizing > Stock Picking
A mediocre investment with appropriate sizing beats a brilliant investment with reckless sizing. I've seen more portfolios destroyed by oversized positions in "sure things" than by bad stock picks.
My rule: No single position should exceed 5% of my portfolio at cost basis. No sector should exceed 20%. These constraints force discipline when conviction runs high.
The Paradox
Counterintuitively, this risk-first approach often leads to better returns. By avoiding catastrophic losses, you stay in the game long enough for compounding to work its magic. The tortoise wins because it never has to recover from a 50% drawdown.