Prediction Market Bankroll Management: Never Blow Up Your Account

The primary factor behind skilled forecasters stumbling in prediction markets isn't inaccurate forecasting — it's inadequate capital allocation. Even a sound probability assessment becomes worthless if a rough patch depletes your entire stake. This guide outlines the system that safeguards against catastrophic losses.

The Kelly Criterion: The Mathematical Foundation

The Kelly Criterion determines the mathematically ideal percentage of your capital to allocate to 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. Whilst Kelly delivers mathematical optimality when probabilities are certain, our estimates always 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 downswings occur even when you possess genuine edge. Following a 20% loss, cut your stake sizes in half until you climb back to your previous peak. This approach shields you from turning a temporary slump into permanent damage.

FAQ

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

$500-1,000 gives sufficient resources to build a diversified portfolio across 10-20 positions using half-Kelly sizing. Anything below $100 constrains your position sizing so severely that disciplined systematic approaches become impractical.

What should I do after a winning streak?

Increase your caution, not your confidence. Successful runs breed complacency. Maintain your systematic sizing discipline irrespective of how well you've performed lately.