Prediction Market Bankroll Management: Never Blow Up Your Account

The biggest reason talented forecasters fail at prediction markets is not bad predictions — it's poor bankroll management. A correct probability estimate means nothing if a single bad streak wipes your account. Here's the framework that prevents this.

The Kelly Criterion: The Mathematical Foundation

Kelly Criterion gives the theoretically optimal fraction of your bankroll to bet on each 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. Kelly is mathematically optimal for known probabilities, but since our probability estimates have uncertainty, half-Kelly provides better risk-adjusted outcomes.

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

Statistical downswings happen even with genuine edge. After a 20% drawdown, reduce position sizes by 50% until you recover to the previous high-water mark. This prevents a bad streak from becoming catastrophic.

FAQ

How much starting capital do I need for serious prediction market trading?

$500-1,000 provides enough capital to properly diversify across 10-20 positions using half-Kelly sizing. Under $100, position size constraints limit your ability to apply systematic principles.

What should I do after a winning streak?

Be more skeptical, not less. Winning streaks create overconfidence. Stick to your systematic sizing rules regardless of recent performance.