In this guide
The most common pitfall for skilled forecasters participating in prediction markets stems not from inaccurate forecasts — it's inadequate management of capital reserves. Even the most precise probability assessment becomes worthless if a prolonged losing run depletes your entire account. This guide outlines the essential strategy to safeguard against such catastrophe.
The Kelly Criterion: The Mathematical Foundation
The Kelly Criterion determines the theoretically ideal proportion of your capital to allocate to each individual trade: f = (bp - q) / b
- b = net odds received (e.g., if YES costs 0.40, b = 1.5)
- p = your probability estimate
- q = 1 - p
- Result: optimal fraction of bankroll for this position
In practice: use half-Kelly. Whilst Kelly delivers mathematical optimality under conditions of perfect probability knowledge, our real-world estimates carry inherent uncertainty, making half-Kelly the superior choice for risk-adjusted performance.
Hard Rules: Never Break These
- Maximum 5% of bankroll per single position — no exceptions regardless of conviction
- Maximum 25% of bankroll in any single correlated cluster — e.g., all US election markets
- Stop-loss: if you lose 25% of your starting bankroll in a month, stop trading for the rest of the month
- Never add to a losing position to "average down" — reevaluate the fundamental thesis first
Drawdown Recovery
Inevitable periods of underperformance occur even amongst traders with demonstrable edge. Following a 20% loss from peak, cut your position sizes in half until you return to your previous peak level. This approach ensures that temporary adversity does not spiral into irreversible damage.
FAQ
- How much starting capital do I need for serious prediction market trading?
- $500-1,000 furnishes sufficient resources to build a properly balanced portfolio spanning 10-20 positions using half-Kelly methodology. Below $100, position constraints become prohibitively restrictive, undermining your capacity to execute disciplined, systematic approaches.
- What should I do after a winning streak?
- Increase your critical scrutiny rather than your confidence. Success breeds complacency and inflated self-assurance. Maintain adherence to your predetermined sizing discipline independent of recent results.